==========
Wed's Help
==========

The following help covers the basic features of wed. There are some important
caveats to keep in mind when reading this documentation.

First caveat. Wed is designed to be an XML editor that provides on the fly
validation, and *only* this. Consequently, wed has no notion of a "document
collection" and provides no means to load documents from a collection or save
documents under some name into a collection. Functions such as these are to be
provided by the larger application in which wed is being used. **The following
documentation does not cover the functions which are outside the scope of wed.**

Second caveat. The functions of wed are exposed to the user through *editing
modes* (usually just referred to as "modes"). It is possible to use wed with
custom modes that present the document differently from what the generic mode
does, or include toolbars, menus, dialogs, etc. **The following documentation
covers only what the generic mode (bundled with wed) provides.** Custom modes
will have to provide their own documentation.

Third caveat. Make sure that wed is supported on your browser before `filing a
bug report <https://github.com/mangalam-research/wed/issues>`_. See `Browser
Requirements`_.

Editing Controls
================

Wed divides the screen into various areas.

Toolbar
-------

Above the validation progress bar, wed presents a toolbar that allows to perform
some operations through the mouse.

.. note:: Wed does not include in the toolbar a button for every single
          operation that may be performed through the keyboard. It includes only
          some operations by default, and modes may add more custom operations
          to the toolbar.

.. figure:: help_images/toolbar.png
   :align: center
   :alt: This image shows the default toolbar.

   The default toolbar.

If you hover the mouse pointer over a button, you will get a prose description
of what the button does. In the image above, from left to right the buttons
perform the following actions:

* Save the document.
* Undo.
* Redo.
* Decrease the `label visibility level <Label Visibility_>`_.
* Increase the `label visibility level <Label Visibility_>`_.
* Remove markup from mixed content.
* Toggle attribute autohiding off and on.
* Set the selection mode to `span <Span Mode_>`_.
* Set the selection mode to `unit <Unit Mode_>`_.

The attribute autohiding button is a toggle. When autohiding is on, the button
is pressed down, as shown by shadows. When autohiding is off, the button is
flat, as shown by the absence of shadows.

The buttons that set the selection mode are mutually exclusive. The button which
corresponds to whichever mode is active will is pressed down.

Mode-specific buttons may appear to the right of the double bar. The buttons
that appear there are those that correspond to the mode in effect at the caret
location.

The Validation Progress Bar
---------------------------

As you edit your document, wed validates your document according to the Relax NG
schema that was specified when wed was started. Whenever you make a change to
the document, wed revalidates the document.

.. note:: At the moment, wed itself does not provide a GUI to select different
          schemas. It is up to the software that uses wed to provide to the user
          the means to select a schema. How to do this depends on the needs of
          the project. For instance, wed is used in `BTW
          <https://btw.mangalamresearch.org>`_ to allow the editing of scholarly
          documents. There there can be only one schema in use and thus no need
          to ask the user to select a schema.

The validation progress bar is located above the editing pane. The image below
shows the general location of the bar.

.. figure:: help_images/validation_bar.png
   :align: center
   :scale: 50%
   :alt: This image shows the location of the validation bar, above the editing
         pane.

   The location of the validation bar.

When an document is first loaded, or when a revalidation occurs, the bar starts
empty (all white). It is progressively filled with color as validation
proceeds. For small documents, validation will occur very quickly and
consequently the user will see the bar instantly fill to completion. The color
of the bar and the status that appears in the center of the bar will vary
depending on the results of validation.

* The bar will be green and the status will be "valid" if validation is complete
  and the document is valid.

  .. figure:: help_images/validation_bar_valid.png
     :align: center
     :alt: The validation bar is green and shows the status "valid".

     A validation bar indicating a valid document.

* The bar will be red and the status will be "invalid" if the document is not
  valid.

  .. figure:: help_images/validation_bar_invalid.png
     :align: center
     :alt: The validation bar is red and shows the status "invalid".

     A validation bar indicating an invalid document.

* The bar will be blue and the status will be "working" as long as validation is
  not complete.

  .. figure:: help_images/validation_bar_working.png
     :align: center
     :alt: The validation bar is blue and shows the status "working".

     A validation bar indicating the validation is not complete.

* There is also a "stopped" status, which you should never see.

Modification and Save Status
----------------------------

On the left side of the screen, at the top, wed shows you the modification and
save status of the document being edited.

.. figure:: help_images/modification_and_save_status.png
   :align: center
   :scale: 50%
   :alt: This image shows the location of the modification and save status, on
         the top left side of the screen.

   The location of the modification and save status.

The rectangle on the left is the modification status. A green modification
status indicates that the document has not been modified since it has last been
loaded or last saved. To the right of the modification status is the save
status. It starts gray to indicate that the document has never been saved
*during the current editing session.*

.. figure:: help_images/unmodified_unsaved.png
   :align: center
   :alt: An unmodified and unsaved status.

   The status shown for a document that has not been modified since last loaded
   and has not yet been saved in this editing session.

When you modify the document, the modification status becomes orange and
contains an asterisk to indicate that the document in the editor has
modifications that have not been saved yet.

.. figure:: help_images/modified_unsaved.png
   :align: center
   :alt: A modified and unsaved status.

   The status shown for a document that has been modified since last loaded and
   has not yet been saved in this editing session.

When you save manually (for instance, by doing :kbd:`Ctrl-s`), the modification
status returns to green and the saved status becomes green. The saved status
also tells you how long ago the last save occurred. Hovering on the save status
brings up a tooltip telling you what kind of save last occurred: autosave, or
manual save.

.. note:: The delay between autosaves is configurable, and can be turned off by
          the application which makes use of wed. The availability of autosaves
          and the delay between autosaves is determined by the application which
          makes use of wed for editing.

.. figure:: help_images/unmodified_manual_save.png
   :align: center
   :alt: An unmodified and manually saved status, with tooltip.

   The status shown for a document that has been manually saved moments ago.

The save status will update periodically to show approximately how long ago the
document was last saved.

.. figure:: help_images/unmodified_manual_save_minutes_ago.png
   :align: center
   :alt: An unmodified and saved status, which occurred minutes ago.

   The status shown for a document that has been saved almost five minutes ago.

The Error Pane
--------------

On the left of the screen, under the modification and save status, you can find
the error pane. This is where XML validation errors are shown to the user.

.. figure:: help_images/error_pane.png
   :align: center
   :alt: The location of the error pane.

   The error pane.

The error pane is collapsible. It can be collapsed or expanded by clicking on
the pane's heading. Clicking on `error markers <Error Markers_>`_ in the editing
pane will expand the error pane. Clicking on an error description in the error
pane will scroll the editing pane to the location of the error. It will also
make the error "selected". The selected error has its description blinking in
the error page and has its error marker blinking in the editing pane.

.. figure:: help_images/click_on_error_description.gif
   :align: center
   :alt: Shows what happens when the user clicks on an error description.

   Clicking on an error description scrolls the editing pane to that error.

The Navigation Pane
-------------------

The navigation pane is a basic functionality of wed but will be visible only if
a mode makes use of it. **The generic mode does not make use of the navigation
pane.** The generic mode is meant to be truly *generic* and thus does not know
what elements serve as section headings in a document. Therefore, it does not
know how to build the content of the navigation pane. So if you are using the
generic mode, you won't see it.

Custom modes that make use of the pane will show this pane under the
`modification and save status <Modification and Save Status_>`_, above the error
pane.

.. figure:: help_images/navigation_pane.png
   :align: center
   :alt: Shows where the navigation pane is situated.

   The navigation pane.

The user can click on the headings in the navigation pane to quickly scroll the
editing pane to the corresponding area of the document. Some modes may also
support bringing up special contextual menus on the headings of the navigation
pane.

The Minibuffer
--------------

As the name suggests, this is inspired by Emacs' minibuffer. However, wed's
minibuffer is much more primitive than Emacs'. The minibuffer is a space that
wed uses to quickly prompt for input *instead of* bringing up a dialog box. It
allows for quick operations like `quick searches <Quick Search_>`_. When it is
not in use, the minibuffer is empty. A prompt appears there when wed prompts the
user.

.. figure:: help_images/minibuffer.png
   :align: center
   :alt: Shows the minibuffer just under the editing pane.

   The minibuffer.

In the example above, the minibuffer is prompting the user for a quick search,
forward in the document.

The Location Bar
----------------

The location bar appears right under the minibuffer. It indicates the hierarchy
of elements that contain the caret. Each XML element in the hierarchy is
separated from the next by a forward slash (``/``).

.. figure:: help_images/location_bar.png
   :align: center
   :alt: Shows where the location bar is situated.

   The location bar.

In the example above, reading from the end of the location bar, the caret is
located in a ``note`` element contained by a ``notesStmt`` element contained by
a ``biblFull`` element, etc.

The Editing Pane
----------------

The editing pane is where the document being edited is displayed and where most
changes to a document are performed. It appears under the validation progress
bar, above the location bar and to the right of the error pane.

.. figure:: help_images/editing_pane.png
   :align: center
   :alt: Shows where the editing pane is located.

   The editing pane.

If the document is too long for the space given to wed, the editing pane will
show a scroll bar on the right that allows scrolling the document.

We will now go over each distinctive element of the editing pane.

The Caret
~~~~~~~~~

The caret indicates where the document is being edited. It is a blinking
vertical bar. It can be moved by left clicking. When the caret is already in the
document, the arrow keys on your keyboard can be used to move the caret.

.. figure:: help_images/caret.gif
   :align: center
   :alt: Shows the caret.

   The caret can be moved with left clicks of the mouse or the arrow
   keys.

The element that contains the caret also acquires a pale yellow background color
while the caret is in it. Only the element which immediately contains the caret
acquires this color. The elements that contain this element do not change
background color.

Placeholders
~~~~~~~~~~~~

Empty elements contain placeholders. The placeholders are meant to help users
easily put the caret in empty elements. Without the placeholder, the start and
end labels of empty elements would be immediately adjacent, and getting the
caret between them would be more difficult. (It would require clicking on the
start label and moving right or clicking on the end label and moving left.) When
an element is edited to contain text or other elements, it loses its
placeholder. When an element is emptied it gains a placeholder.  When the caret
is in a placeholder, the placeholder blinks to indicate that it contains the
caret.

.. figure:: help_images/placeholder.gif
   :align: center
   :alt: Text editing add and removes placeholders.

   The ``hi`` element gains a placeholder when the text is removed,
   and loses the placeholder when text is added back.

Placeholders also appear as the value of those attributes which have no value
set.

Element Labels
~~~~~~~~~~~~~~

By default, the generic mode bundled with wed shows the start of each XML
element with a start label, and the end of each XML element with an end
label. The start and end labels can be distinguished from one another by the
fact that a start label ends with a right angle bracket (``>``) and an end label
starts with a left angle bracket (``<``).

.. note:: It is possible for custom modes to display elements using more
          specialized rendering, and omit the start and end labels. For
          instance, a custom mode could distinguish "paragraph" elements through
          line breaks and indentation, and omit the start and end labels of
          these elements.

.. figure:: help_images/start_end_labels.png
   :align: center
   :alt: An example of start and end labels.

   This figure contains a total of 8 labels: two start labels for two elements
   ``p``, and the corresponding two end labels, two start labels for two
   elements ``hi`` and the corresponding two end labels.

Clicking on an element's label selects the element and allows the user to
perform actions on the element as a whole. When the element is selected, both
the start and end labels are colored orange.

.. figure:: help_images/selected_labels.png
   :align: center
   :alt: An example of selected labels.

   This figure shows a ``p`` element which is selected. Its labels are orange.

Right-clicking on an element label will bring up a `contextual menu <Contextual
Menus_>`_ appropriate for the element. Start labels may contain the attributes
associated with the XML element to which the label belongs. For each attribute,
the label first shows the attribute's name, followed by the equal sign (``=``)
and the attribute value in double quotes (``"``). The attribute's value appears
in black on a white background.

.. figure:: help_images/attributes.png
   :align: center
   :alt: An example of attributes in a start label.

   This figure shows a ``p`` element with the attributes ``rend`` and ``style``.

Modes may configure wed so that some elements are hidden if the caret is out of
a start label, but shown then the caret is moved inside the start label. Labels
that have hidden attributes will show an ellipsis (``...``) before the right
angle bracket (``>``).

.. figure:: help_images/attributes_ellipsis.png
   :align: center
   :alt: An example of start label with hidden attributes.

   This figure shows a ``div`` element with the ellipsis that indicates some
   attributes have been hidden.

When the caret is moved inside the start label, the hidden attributes are shown,
and they are hidden again as soon as the caret is moved out of the start label.

.. figure:: help_images/attributes_shown.gif
   :align: center
   :alt: An example of start label with hidden attributes that are shown.

   This figure shows a ``div`` element with its hidden attributes shown.

.. note:: Attribute visibility is determined by the mode being used to edit the
          file, and how this mode is configured. The generic mode by default
          shows attributes. It is possible for an application using wed to
          configure the generic mode to hide attributes. Custom modes may be
          designed to hide attributes too.

.. note:: When a double quote appears as part of an attribute's value, wed will
          show the double quote as a double quote. In other words, it does not
          visually escape it. **However, wed does encode double quotes appearing
          in an attribute's value properly.**

Whenever the mode being used has provided element documentation, hovering over a
label will bring up a tooltip with the documentation of the element.

.. figure:: help_images/label_tooltip.png
   :align: center
   :alt: An example of a start label with its tooltip open.

   This figure shows a label for a ``p`` element whose tooltip is open. The
   tooltip contains documentation on the element.

.. note:: Whether documentation is actually available depends on the mode being
          used and how the mode was configured and packaged with wed.

          Element documentation is not provided by wed itself. The generic mode
          used in Wed's demo is set to work with TEI documents, and thus provide
          documentations on TEI elements. This documentation was converted for
          use by wed but its contents was created by the authors of the TEI
          schema. Wed merely extracted it.


Label Visibility
''''''''''''''''

The editing modes of wed can be designed to assign different levels of
visibility to labels. Imagine for instance a mode that represents breaks in
paragraphs through line breaks and indentation, or foreign text by showing it in
italics, and so on. For each element that is represented on screen using
styling, it is usually not necessary to show the end and start labels of the
element: the presence of the element and its extent is already visible through
styling.

.. figure:: help_images/default_label_visibility.png
   :align: center
   :alt: A document shown at default label visibility. There is no
         element label visible in the picture.

   This is an example of the situation described above in the text.

It still may be useful sometimes for users to see the labels. Perhaps there is
an operation they want to perform that is easier to do with labels. In such
case, wed allows changing the label visibility level.

.. figure:: help_images/increased_label_visibility.png
   :align: center
   :alt: A document shown at increased label visibility. Every single element
         gets labels.

   This is an example of the same document shown earlier but with increased
   label visibility. You'll notice that the word "prasāda" now has start and end
   labels for ``foreign``. Paragraphs also have the ``p`` element.


Error Markers
~~~~~~~~~~~~~

Error markers indicate where in the document there is a validation error. They
appear as red rectangles at the location of the errors they mark.

.. figure:: help_images/error_marker.png
   :align: center
   :alt: An error marker.

   An error marker appearing in an attribute value.

Clicking an error marker will expand the error pane if it was closed, and will
scroll the pane to show the error message corresponding to the error
marker. Both the marker and the error message will become selected. Selected
markers and their message blink slowly to indicate that they are selected.

.. figure:: help_images/error_marker_click.gif
   :align: center
   :alt: Clicking an error marker.

   When an error marker is clicked, the marker and the error's description
   become selected.

Contextual Menus
~~~~~~~~~~~~~~~~

Right-clicking on element labels or in the text contained by elements or
attributes brings up a contextual menu. As the term "contextual" suggests, the
content of the menu is determined by the location where the contextual menu is
being invoked. In particular, the list of operations available in the menu is
determined by what the Relax NG schema that governs the editing session allows
in the specific location where the menu was invoked. For instance, if an element
allows only the attributes ``a`` and ``b``, and ``b`` is already present on the
element, then the contextual menu that you get when right-clicking on the start
label of the element will show only an option to add the ``a`` attribute,
because adding a ``b`` attribute again would not be valid.

.. figure:: help_images/contextual_menu.png
   :align: center
   :alt: A contextual menu.

   This is a contextual menu brought up on the start label of the ``title``
   element.

The top of the contextual menu contains buttons and an input field that allow
filtering the list of options presented by the menu. When editing a document
using a complex schema, there can be dozens of options available. Filtering
helps finding the desired option quickly.

The input field filters the options that pertain to attributes or elements on
the basis of attribute name or element name. It filters other options on the
basis of the name of the option shown in the menu. When you bring up the
contextual menu, the input field is focused automatically, so you can type in it
right away, without having to focus it with the mouse.

.. figure:: help_images/contextual_menu_text_filter.gif
   :align: center
   :alt: Using the input field to filter entries in the contextual menu.

   The user brings up a contextual menu and filters options to those that
   contain the text ``xml``.

The buttons above the input field allow filtering the list of options according
to characteristics other than text. The buttons are divided into two groups: the
first group filters by the kind of operation performed, the second group filters
by what kind of XML construct the operation affects. Hovering the mouse over
each button will give you a description of the filtering performed by the
button. The buttons in the first group filter as follows:

* |add| filters the list of options to those that add content. For instance,
  adding elements and attributes.

* |delete| filters the list of options to those that delete content. For
  instance, deleting elements and attributes.

* |wrap| filters the list of options to those that wrap content into an
  element. For instance, wrapping text into a new element.

* |unwrap| filters the list of options to those that unwrap content. For
  instance, unwrapping an element.

* |other| filters the list of options to those that are not in one of the
  previous categories.

.. |add| image:: help_images/filter_add.png
.. |delete| image:: help_images/filter_delete.png
.. |wrap| image:: help_images/filter_wrap.png
.. |unwrap| image:: help_images/filter_unwrap.png
.. |other| image:: help_images/filter_other.png

The buttons of the second group filter as follows:

* < filters the list of options to those that perform operations on XML
  elements. For instance, if you select this filter, then all options that edit
  attributes would be removed.

* @ filters the list of options to those that perform operations on XML
  attributes. For instance, if you select this filter, then all options that
  edit elements will be removed.

* |other| filters the list of options to those that are not in one of the
  previous categories. Therefore, it would filter the list of options to remove
  those options that perform operations on elements or attributes.

The first characters typed into the input field can serve to select the buttons
listed above by means of the keyboard rather than using the mouse. When one of
these keys is used to select a button, this key only performs the task of
selecting a button *but does not appear in the input field*. The keys recognized
are:

* :kbd:`+` selects |add|

* :kbd:`-` selects |delete|

* :kbd:`,` selects |wrap|

* :kbd:`.` selects |unwrap|

* :kbd:`?` selects |other| in the first group of buttons. That is, it filters
  options to those that do not add, delete, wrap or unwrap.

* :kbd:`<` selects <

* :kbd:`@` selects @

* :kbd:`!` selects |other| in the second group of buttons. That is, it filters
  options to those that do not operate on elements or attributes.

* :kbd:`ESC` resets filtering. It will clear all the filtering buttons and will
  clear the input field. If no filtering was in effect, then it will close the
  contextual menu.

Once a button has been selected, *either with the mouse or by using one of the
keys above*, then the keys that select filters from that group no longer have
for effect to select filters. Instead, they will be added into the input field,
just like any other key. Here are some examples of this behavior:

* If the user opens a contextual menu and types ``+``, this will have for effect
  to select the |add| button and filter the options to those that add
  content. So far so good. Then if the user types ``-``, this will *not*
  unselect |add| to select |delete| instead. Rather, the ``-`` character will
  appear literally in the input field so that the end result will be that only
  options that add content and operate on attribute or elements which have ``-``
  in their name.

* If the user opens a contextual menu and types ``+``, and then ``@``, the |add|
  and @ buttons will be selected and the list will show only those options that
  add attributes. After the user types ``+``, the keys associated with the first
  group of buttons cease to select buttons, but those associated with the second
  group continue to be available to select one of the buttons in the second
  group. Once ``@`` has been typed too, then none of the keys that select
  buttons perform button selections anymore.

Resetting filtering by typing :kbd:`ESC` resets this behavior. In other words,
the keys that select buttons become operational again.

It is possible to select an option from the contextual menu by using the up and
down arrow keys on the keyboard and typing :kbd:`ENTER` on the desired
option. :kbd:`ESC` closes the contextual menu without performing a selection,
provided there is no filtering in effect, otherwise it will clear the
filtering. If filtering is in effect, then using :kbd:`ESC` twice in a row will
close the contextual menu.

Completion Menus
~~~~~~~~~~~~~~~~

If the schema used to edit the document specifies an enumerated list of possible
values, wed will present the user with a completion menu. A common case is for
attributes that may take only a limited set of values. Upon first placing the
caret in a location that can be auto-completed, wed will present the whole list
of possible values.

.. figure:: help_images/completion_initial.png
   :align: center
   :alt: A completion menu in its initial state.

   The user just clicked into the ``sample`` attribute. Wed presents the list of
   possible values.

The user may use the arrows on the keyboard to go up and down the list of values
to highlight a value, and hit :kbd:`ENTER` to insert it as the attribute
value. Note that hitting :kbd:`ENTER` when no value is highlighted in the menu
will insert the first value in the menu. Or the user may start typing a value at
the keyboard. As a value is entered, the list of completions will be narrowed to
those values that begin with the characters entered by the user. The matched
prefix will be bolded in the list of values. The user may then use the keyboard
arrows and :kbd:`ENTER` to complete the value already begun. It is possible also
to just type the whole value at the keyboard (which may be faster, in some
cases, than fiddling with a menu), in which case the menu will close once the
value is complete.

.. figure:: help_images/completion_typing.gif
   :align: center
   :alt: A completion menu as the user types in.

   The user types ``med`` into the completion menu and then hits :kbd:`ENTER` to
   complete the value.

Replacement Menus
~~~~~~~~~~~~~~~~~

Replacement menus are similar to completion menus. Completion menus appear
automatically but only *when the document contains a value that can be
completed*. Given an attribute that has a limited set of possible values, if the
attribute is already filled with a complete value, then the completion menu does
not appear. Suppose an attribute ``height`` which can take the values ``high``,
``medium``, ``low``, and it is already filled with the value ``medium``. If you
want to change the value, you won't be able to use the completion menu, because
there's nothing to complete since ``medium`` is already complete. So if you want
to change the value with the help of the editor, you have to use a replacement
menu by hitting :kbd:`Ctrl-?`.

Replacement menus are available in the same places completion menus are
available. The list of values they offer is the same as the list provided by a
completion menu in the same location. Choosing an item from the list in a
replacement menu replaces the entire attribute value with the item selected.

Note that replacement menus, contrarily to completion menus, do not support
changing the document while the menu is open. You need to exit the menu before
you can continue editing the document. If you don't want to make a change, click
outside the menu or hit :kbd:`ESCAPE`.

.. figure:: help_images/replacement_menu.png
   :align: center
   :alt: A replacement menu.

   The user just brought up the replacement menu in the ``sample`` attribute.

Kinds of XML Operations
=======================

Wed divides operations on elements and attributes into a few categories:

* Adding. Such operations are usually marked with the |add| symbol. These are
  operations that add entirely new elements or attributes to the document. They
  normally do not operate on selections.

.. figure:: help_images/adding.gif
   :align: center
   :alt: A user adds an element.

   The user adds an ``abbr`` element to the document.

* Deleting. Such operations are usually marked with the |delete| symbol. These
  are operations that remove whole elements or attributes from the
  document. They normally do not operate on selections.

.. figure:: help_images/deleting.gif
   :align: center
   :alt: A user deletes an element.

   The user deletes an ``abbr`` element from the document.

* Wrapping. Such operations are usually marked with the |wrap| symbol. These
  operations add an element around a section of the document being edited. The
  section is indicated by clicking and dragging with the mouse to select a part
  of the document. Therefore, wrapping operations appear in the contextual menu
  only if a selection is in effect. They "wrap" the selection in a new element.

.. figure:: help_images/wrapping.gif
   :align: center
   :alt: A user wraps an element.

   The user wraps text in an ``abbr`` element.

* Unwrapping. Such operations are usually marked with the |unwrap| symbol. This
  is the reverse of wrapping. These operations operate on an element so as to
  remove the element but put the element's original content in place of the
  element being removed. They normally do not operate on selections.

.. figure:: help_images/unwrapping.gif
   :align: center
   :alt: A user unwraps the content of an element.

   The user unwraps the content of an element.

Searching
=========

Wed offers two types of searches: quick searches, and dialog searches.

Moreover, wed will search through text in two possible contexts. Do not confuse
context and scope. The scope is the range of the document within which the
search operates. The context determines what *in this range* is part of the
search. Here are the two contexts:

* Element text. This encompasses only the text of elements. For instance,
  searching for ``some`` in the XML ``<some.element some.attribute="some
  value">some text</some.element>`` would only hit the word ``some`` that
  appears before the word ``text`` and nothing else.

  Note that because this context ignores the XML tags, it is possible for it to
  perform matches across element boundaries. For instance if you search for ``I
  am happy`` in the XML ``<p>I <bold>am</bold> happy</p>``, the search will
  match the entire content of ``p``. That is, the ``bold`` element does not
  prevent the match.

* Attribute values. This encompasses only the values of element attributes. In
  the example above, a search for ``some`` would match only the word ``some``
  appearing before ``value``.

  Note that this kind of search does not span attributes. For instance, if you
  have ``<p type="abc" subtype="def"/>`` and search for ``abcdef`` you will
  **not** get a match that spans the values of ``@type`` and ``@subtype``. This
  is probably not a desirable behavior at any rate, but we're mentioning it,
  just in case.

It is not possible to search for element names or attribute names with the quick
search or dialog search. Nor is it possible to search for text which is purely
created for the sake of displaying the XML. Here's an example of the
latter. Suppose the following document::

    <doc>
      <p>
       Johnson demonstrated (<ref target="/some/bibliographical/item"/>) that ...
      </p>
    </doc>

In this example, ``ref`` is a reference to a bibliographical item. Your wed
mode, fetches the bibliographical information and shows it instead of showing
the XML element as-is. So what you see is something like::

    doc >
     p >
      Johnson demonstrated (Johnson, Five Ways to Eat Sushi) that ...
     < p
    < doc

``doc >``, ``p >``, ``p <`` and ``< doc`` are the start and end labels that
normally shows for elements. The string ``Johnson, Five Ways to Eat Sushi`` is
text that is not part of the XML but that the editing mode adds when it shows
you your document. It is more informative than ``<ref
target="/some/bibliographical/item"/>``. At any rate, neither searching through
element text or element attributes can find that text.

If you need to search for element names, attribute names or text created for
display purposes, you must use your browser's built-in search.

Quick Search
------------

You can use :kbd:`Ctrl-f` to quick-search forward, and :kbd:`Ctrl-b` to
quick-search backwards. When you hit either of these shortcuts, the `minibuffer
<The Minibuffer_>`_ becomes active and prompts you for a search term. As you
type the term you are searching for, wed will search through the document and
highlight in yellow the term it finds. To move to another hit, press
:kbd:`Ctrl-f` or :kbd:`Ctrl-b` again. Type :kbd:`ESCAPE` to end the search.

If you have a selection in effect when you start the search, the search will be
scoped to that selection. That is, the search will only search between the start
and end of the selection. (The selection disappears while you are searching:
this is normal and a current limitation of wed.) If you have no selection in
effect when you start the search, then the whole document will be searched.

.. figure:: help_images/minibuffer.png
   :align: center
   :alt: Shows the minibuffer just under the editing pane.

   The minibuffer.

In the example above, the minibuffer is prompting the user for a quick search,
forward in the document. You can see the word "original" was found and
highlighted in yellow. When you hit the end of the search scope in either
direction, the highlight will disappear. If you then hit the shortcut to
continue in the same direction you were going, the search will continue from the
start of your search scope.

Dialog Search
-------------

You can use :kbd:`Ctrl-Shift-f` to search forward, and :kbd:`Ctrl-Shift-b` to
search backwards. Dialog searches are thus named because they bring up a dialog
box to provide the user with more search options than the quick searches.

Just like quick searches, if you have a selection in effect when you start the
search, the search will be scoped to that selection. That is, the search will
only search between the start and end of the selection. (The selection
disappears while you are searching: this is normal and a current limitation of
wed.) If you have no selection in effect when you start the search, then the
whole document will be searched.

.. figure:: help_images/dialog_search.png
   :align: center
   :alt: Shows the dialog that is brought up by dialog searches.

   A dialog search.

The "Search for:" field is where you type the term you are searching for.

The "Replace with:" field is where you type the text you want to use to replace
the hits you find.

The "Direction": buttons determine in which direction the search goes. The
direction is initially determined by which shortcut you use to bring up the
search but you may change it later if you want.

The "Context:" buttons determine what is searched. There are two possible
contexts:

* "Only element text": this searches only through the text of
  elements. Consequently, attributes are not searched.

* "Only attributes": this searches only through the attribute values of
  elements. Consequently, the text of elements is not searched.

The buttons:

* "Find" looks for the next match.

* "Replace and Find" replaces the current match and finds the next.

* "Replace All" replaces all matches until the search reaches a boundary of the
  search scope currently in effect. The boundary depends on the direction of the
  search. If searching forward, the boundary marking the end of the search is
  the end of the scope. If searching backwards, it is the start of the scope.

* "Close" closes the dialog.

.. warning:: Wed cannot replace hits that select an ill-formed portion of an XML
             document. For instance, you have the XML ``tea<bold>pot</bold>``
             and you search for ``ap``. If we mark the start and end of the hit
             with the element ``mark`` we'd have
             ``te<mark>a<bold>p</mark>ot</bold>``. This is not well-formed XML
             because ``mark`` and ``bold`` are straddling. Wed cannot replace
             such cases, and will disable the "Replace and Find" button when you
             land on such a case.

             Note however that the "Replace All" button is never disabled. When
             you use "Replace All", wed replaces all instances that it **can**
             replace.

Saving
======

You can save by using :kbd:`Ctrl-s` or whatever means provided by the
application that uses wed. Possible outcomes:

* The data is saved. You will see a message telling you that the data was saved,
  and the `save status <Modification and Save Status>`_ will indicate the data
  was saved.

  .. figure:: help_images/saved_message.png
     :align: center
     :alt: A green message saying "Saved".

     This is the message that a user gets when a document was saved.

* Wed is disconnected from the server. You will get a dialog box saying:

   It appears your browser is disconnected from the server.  Editing is frozen
   until the connection is reestablished.  Dismissing this dialog will retry
   saving. If the operation is successful, you'll be able to continue
   editing. If not, this message will reappear.

  You're effectively prevented from further edits until wed is able to
  reestablish connectivity with the server.

  .. note:: It is possible to configure wed to use other types of saving
            mechanisms than sending data to a server. For instance,
            ``localStorage`` can be used to record data in the browser
            itself. What mechanism wed uses depends on how the application in
            which wed is used has configured wed.

* The server responded to the save request with a message that indicated that
  the document being edited with wed changed on the server. In other words,
  while you were editing a document someone else edited and saved the same
  document, or an automated process modified the document. You'll get a dialog
  box with the following message:

   Your document was edited by someone else since you last loaded or saved
   it. You must reload it before trying to edit further.

  On reload, wed will acquire a fresh copy of the document from the
  server. **The edits you performed on your document will be lost.** Wed is not
  currently equipped to deal with concurrent modifications from multiple
  sources.

  .. note:: This is another instance where application that makes use of wed is
            the party responsible for providing the means to resolve concurrent
            modification conflicts or prevent them from happening in the first
            place.

            The solution is really application-specific. For `BTW`_ we decided
            that locking documents to prevent concurrent modifications was the
            right solution. Another project could conceivably decide to solve
            conflicts in a way similar to what ``git`` does for merge
            conflicts. There's no single answer here.

* There is an application-specific error which prevents saving the data. You
  will see a message in a red notification bubble telling you what error
  happened, and the `save status <Modification and Save Status>`_ will not be
  updated. The content of the error message depends on the specific nature of
  the error. For instance, an application which requires that documents be given
  titles before they are saved could report an error if you try to save a
  document without a title.

Copy, Cut and Paste
===================

Wed allows copying, cutting and pasting parts of a document. When you perform a
copy operation, the data is copied from the document to the clipboard. When you
perform a cut operation, the data is copied from the document to the clipboard,
and is also removed from the document. When you perform a paste operation, the
data is copied from the clipboard to the document. This is not specific to wed
but is the standard way software manipulates the keyboard.

.. note:: Readers needing more details about how copy, cut and paste interact
          with the clipboard should consult general-purpose documentation about
          how to use computers.

Wed supports two selection modes:

* Span mode: a mode by which you must select a span of the document to operate
  on. This is similar to how you would select text in common plain text editors
  like Notepad or word-processors like Word.

* Unit mode: a mode by which you direct the editor to copy or cut entire XML
  structural units, like attributes or elements.

You can use the toolbar or :kbd:`Ctrl-SPACE` to change the selection mode. Wed
operates in a way that prevents mixing data from the two modes described
above. If you start copying data to the clipboard in span mode, then switch to
unit mode and copy more data, then the data you copied in span mode will be
removed from the clipboard. The same is true if you start in unit mode and
switch to span mode.

Span Mode
---------

This mode works mostly like how copy, cut, and paste works in plain text editors
like Notepad, or word-processors like Word. You select a span of the document
and direct the editor to perform an operation on it. However, because wed edits
XML, there are some limitations to what you can do.

Copy
~~~~

Copying contents *as XML* works only if the selection being cut starts and ends
inside the same XML element or the same XML attribute value. The selection can
span over XML elements, provided that it completely contains these elements. If
your selection straddles XML elements, then it will be copied *naively*, and you
will get a notification telling you that your selection was copied as such.

Note that "copied naively" here means that the content will be copied by the
browser itself, as if you were copying text from any web page. This means that
any decorations that wed creates and is part of the selection, will have its
textual content copied.

.. figure:: help_images/invalid_selection_cut.png
   :align: center
   :alt: A selection which cannot be copied as XML.

   This selection cannot be copied as XML because it begins in one ``p``
   element but ends in the subsequent ``p`` element.

.. figure:: help_images/valid_selection_cut.png
   :align: center
   :alt: A selection which can be copied as XML.

   This selection can be copied as XML because it begins and ends in the same
   ``p`` element. There is an ``lb`` element inside the selection, which is
   fine.

Cut
~~~

Cutting will work only if the selection being cut starts and ends inside the
same XML element or the same XML attribute value. The selection can span over
XML elements, provided that it completely contains these elements.

.. figure:: help_images/invalid_selection_cut.png
   :align: center
   :alt: A selection which cannot be cut.

   This selection cannot be cut from the document because it begins in one ``p``
   element but ends in the subsequent ``p`` element.

.. figure:: help_images/valid_selection_cut.png
   :align: center
   :alt: A selection which can be cut.

   This selection can be cut from the document because it begins and ends in the
   same ``p`` element. There is an ``lb`` element inside the selection, which is
   fine.

A selection that cannot be cut can still be copied.

Paste
~~~~~

Wed will attempt parsing the pasted text, and if it is a well-formed XML
fragment, it will insert into your document the *parsed XML*, even if the
original document was plain text. Here's an example. Suppose you have a plain
text editor opened, and you have the text ``<foo>something</foo>`` in it. If you
select that text and paste it into wed, wed will create a ``foo`` element that
contains the text ``something``. It will not paste the text
``<foo>something</foo>`` *as text*.

If the text in the clipboard is not well-formed XML, then wed will insert it
into your document as text. So if you have the copy the text ``<foo blah</foo>``
from your plain text editor, and paste it into wed, this will be pasted *as
text*.

Note that pasting into attribute values always pastes the clipboard data as text
because attributes cannot contain anything else than text.

Unit Mode
---------

In unit mode, the editor copies entire XML structural units. There are two kinds
of XML structural units that wed operates on:

* attributes,
* elements.

.. note:: We talk of "units" because other candidate terms already have specific
          meanings in XML. We cannot talk of "elements mode" because XML
          elements are just *one* specific type of XML structure, and the mode
          also works on attributes, which are not elements. We cannot talk of
          "entities mode" because entities are another specific XML
          structure. "Unit" was one term that does not already have a special
          meaning in basic XML parlance.

Besides operating on XML structural unit, unit mode also allows a kind of
operation that span mode does not allow: it allows adding to the contents of the
clipboard instead of replacing it. So besides copy and cut, you can also
copy-add and cut-add.

Indicating Units
~~~~~~~~~~~~~~~~

In this mode you do not use a selection to indicate which unit you want to
operate on. Indeed, **you cannot set a selection while in unit mode**. Instead,
when you copy or cut, the editor will copy or cut the smallest unit enclosing
the current caret position. We call it the "smallest enclosing unit", for short.

.. note:: People who are used to think of XML as a tree of nodes might find it
          easier to use an alternative way to think about how units are
          selected. The "smallest enclosing unit" is always equivalent to the
          tree leaf that immediately contains the caret, with the caveat that
          text nodes are ignored. For instance, if one imagines the XML document
          as a DOM tree and the caret is in a text node, then the smallest
          enclosing unit is the element which contains the text node, not the
          text node itself.

Look at the following example:

.. figure:: help_images/caret_in_attribute.png
   :align: center
   :alt: A caret in an attribute.

In this example, the caret is in the ``rend`` attribute of the first ``p``
element. The units that enclose the caret are:

* the attribute ``rend``,
* the element ``p`` (the first one),
* the element ``body``,
* the element ``text``.

``rend`` is the *smallest* enclosing unit because all other enclosing units
contain more data than ``rend`` does. For instance, ``p`` contains another
attribute besides ``rend`` and contains text.

Consider this example:

.. figure:: help_images/caret_in_text.png
   :align: center
   :alt: A caret in text.

In this example, the caret is in the text of the first ``p`` element. The units
that enclose the caret are:

* the element ``p`` (the first one),
* the element ``body``,
* the element ``text``.

``p`` is the *smallest* enclosing unit because all other enclosing units contain
more than ``p``. For instance, ``body`` contains two other elements besides the
``p`` element in which the caret is located.

Consider this similar example:

.. figure:: help_images/caret_in_element_name.png
   :align: center
   :alt: Caret in an element's name.

In the example, the caret is at the start of the start label for the element
``p``. Since it is outside of any attribute, then the smallest enclosing unit is
like in the previous example: the first ``p`` element.

Consider this example:

.. figure:: help_images/caret_between_elements.png
   :align: center
   :alt: Caret between elements.

In this example, the caret is just before the first ``p`` element in
``body``. The caret is not in any of the elements that are children of ``body``
(the two ``p`` elements and the ``div`` element). The smallest enclosing element
is ``body``.

Copy and Cut
~~~~~~~~~~~~

Performing a copy replaces the data in the clipboard with the smallest enclosing
unit. A cut is the same as a copy, except that the data that is put into
the clipboard is also removed from the document.

Copy-Add and Cut-Add
~~~~~~~~~~~~~~~~~~~~

The keyboard shortcuts for these operations are those for the non-adding
operations but with the alphabetical letter capitalized. So whereas a plain copy
operation is :kbd:`Ctrl-s`, the copy-add operation is :kbd:`Ctrl-Shift-s`. The
practical difference is that the user must hold the :kbd:`Shift` key to get the
"-add" variant. (On OS X, the corresponding combinations are :kdb:`Cmd-s` and
:kdb:`Cmd-Shift-s`. Again, the practical difference is whether or not the
:kbd:`Shift` key is held.)

A copy-add operation **adds** the smallest enclosing unit to data already
in the clipboard. Suppose you are in unit selection mode, and you put your caret
in an attribute named ``a`` and do a copy. The clipboard data is *replaced* with
the attribute ``a``. Then you put your caret in an attribute named ``b`` and do
a copy-add. The attribute ``b`` is *added* to the attribute already in the
clipboard, so that the clipboard will contain two attributes: ``a`` and
``b``. If you had done a copy instead of a copy-add when you were in ``b``, then
the clipboard would contain only one attribute, the attribute ``b``.

The same thing happens if you place your caret to select elements instead of
attributes. You could copy into the clipboard an element ``p`` from the start of
your document, and then copy-add an element ``quote`` from the end of your
document. The clipboard will contain both elements.

It is important to note that the "..-add" operations do not allow mixing
heterogeneous units in the clipboard:

* if you copy an attribute into the clipboard and then copy-add an element, the
  copy-add operation will do nothing, and you will get a notification.

* if you copy an element into the clipboard and then copy-add an attribute, the
  copy-add operation will do nothing, and you will get a notification.

As usual, the only difference between copy-add and cut-add is that the cut-add
operation copies to the clipboard but *also* removes the copied data from the
document.

Pasting
~~~~~~~

Note that because wed is an XML editor, there are a special considerations
regarding how attributes are handled. Wed does not ever violate the general XML
rule that elements cannot hold the same attribute twice. For instance, this is
not well-formed XML::

    <p n="value one" n="value two">text</p>

Wed does not allow you to create this kind of structure. The consequence of this
is that if you use the copy-add or cut-add operations on an attribute you have
already put into the clipboard, then you are changing the value of that
attribute in the clipboard. Consider the following XML::

    <p n="value one">First paragraph</p>
    <p n="value two">Second paragraph</p>
    <p n="value three">Third paragraph</p>

Suppose you set the editor to unit selection mode, and put your caret in the
``n`` attribute of the first paragraph and copy it. The clipboard contains
``n="value one"``. Then you put your caret into the ``n`` attribute of the
second paragraph, and copy-add it. Because of the XML rule mentioned above, the
clipboard will contain ``n="value two"``. It will not contain two ``n``
attributes.

This XML rule against duplicate attributes applies when pasting too. In the same
example above, if after the operations described earlier, you move the caret to
the third paragraph, and paste, then the paragraph will be changed to::

    <p n="value two">Third paragraph</p>

It will not get two ``n`` attributes.

Undo and Redo
=============

Wed maintains a list of the operations that have been performed on the document
being edited. This list is created anew with each editing session. In other
words, each time you open a document with wed, it creates a new list. You can
use :kbd:`Ctrl-z` to undo the last operation. Undoing again, will undo the
operation before the last one, etc. You can undo as many editing operations as
you want, up to the start of the undo list. Conversely, :kbd:`Ctrl-y` will redo
the operation that was just undone. It is useful in cases where you've undone
more than you meant to.

.. _help_keyboard_shortcuts:

Keyboard Shortcuts
==================

"Shortcut" is a bit of a misnomer, since some of the functions mentioned here
are available only through the keyboard, but we'll stick with it.

In the following table, key names that are more than one character specify the
keys name. For instance, ``SPACE`` is the space bar on the keyboard.

==================== ==================== =====================================
 PC Key               Mac Key             Function
==================== ==================== =====================================
 :kbd:`F1`            :kbd:`F1`           Bring up the help.
 :kbd:`Ctrl-/`        :kbd:`Cmd-/`        Bring up the `contextual menu <Contextual Menus_>`_.
 :kbd:`Ctrl-?`        :kbd:`Cmd-?`        Bring up the `replacement menu <Replacement Menus_>`_.
 :kbd:`Ctrl-[`                            Decrease the `label visibility level <Label Visibility_>`_.
 :kbd:`Ctrl-]`                            Increase the `label visibility level <Label Visibility_>`_.
 :kbd:`Ctrl-SPACE`    :kbd:`Ctrl-SPACE`   Switch to the next `selection mode <Cut, Copy and Paste_>`_.
 :kbd:`Ctrl-z`        :kbd:`Cmd-z`        `Undo <Undo and Redo_>`_ an operation.
 :kbd:`Ctrl-y`        :kbd:`Cmd-y`        `Redo <Undo and Redo_>`_ an operation.
 :kbd:`Ctrl-c`        :kbd:`Cmd-c`        `Copy <Cut, Copy and Paste_>`_ content.
 :kbd:`Ctrl-Shift-c`  :kbd:`Cmd-Shift-c`  `Copy-add <Cut, Copy and Paste_>`_ content.
 :kbd:`Ctrl-x`        :kbd:`Cmd-x`        `Cut <Cut, Copy and Paste_>`_ content.
 :kbd:`Ctrl-Shift-x`  :kbd:`Cmd-Shift-x`  `Cut-add <Cut, Copy and Paste_>`_ content.
 :kbd:`Ctrl-v`        :kbd:`Cmd-v`        `Paste <Cut, Copy and Paste_>`_ content.
 :kbd:`Ctrl-s`        :kbd:`Cmd-s`        `Save <Saving_>`_ content.
 :kbd:`Ctrl-f`        :kbd:`Cmd-f`        `Quick search <Quick Search_>`_ forward.
 :kbd:`Ctrl-b`        :kbd:`Cmd-b`        `Quick search <Quick Search_>`_ backwards.
 :kbd:`Ctrl-Shift-f`  :kbd:`Cmd-Shift-f`  `Dialog search <Dialog Search_>`_ forward.
 :kbd:`Ctrl-Shift-b`  :kbd:`Cmd-Shift-b`  `Dialog search <Dialog Search_>`_ backwards.
==================== ==================== =====================================

.. _help_browser_requirements:

Browser Requirements
====================

Wed is primarily developed using a recent version of Chrome. (But see a note
about Chrome 34 below.)

Here is the list of officially supported browsers, in order of decreasing
priority. The higher a browser is in the list, the less likely you are to run
into issues and the higher the priority for resolving bugs happening with this
browser.

* The latest stable version of Chrome.

* The latest stable version of Edge, but `see the section on Edge <Edge_>`_.

* Versions of Chrome or Edge older than the latest stable version, but not very
  old. (Yeah, this is vague. Sorry about that.)

File an issue on github if you find a problem with one of the supported browsers
above.

We would like to support phone and tablet browsers but due to a lack of
development resources, such support is unlikely to materialize soon. In
decreasing order of likelihood, the following cases are unlikely to ever be
supported:

* Versions of Chrome or Edge older than those mentioned above.

* Firefox. It deserves its own `discussion <Firefox_>`_.

* IE. Support for IE 11 has become too costly. Resuming support for IE is
  extremely unlikely, because wed has accumulated features and methods that do
  not work on these browsers.

* Chrome 34: the luminaries at Google decided to remove ``Attr.ownerElement``
  from Chrome 34. It was reintroduced in Chrome 35. We'll probably never have
  support for Chrome 34.

* Antique browsers.

* Oddball browsers or other software or hardware systems that present web
  pages. (E.g. gaming consoles, smart TVs.)

* Operating systems or browsers no longer supported by their own vendors.

Edge
----

Cut-copy-paste are not working well in Edge, and there is currently no
development resource available to devote to it. The root cause is that the
luminaries who develop Edge cannot be bothered to implement the clipboard API
correctly. See:

* https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/14080506/
* https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/14110451/

At the time of writing this, the bugs were reported over a year ago: response
from Microsoft... crickets.

Firefox
-------

We're hoping that the lack of Firefox support is going to be temporary. The
paragraphs below give the state of Firefox support, in reverse chronological
order (most recent on top):

Update August 2018: Firefox support is still suspended. Geckodriver is plagued
by asinine regressions like `this one
<https://github.com/SeleniumHQ/selenium/issues/5621>`__ Returning DOM elements
is supported on all browsers and has been supported by Selenium since time
immemorial, but they managed to screw it up. *sigh*

Update November 2017: Firefox support is still suspended. The Marionette driver
has been released. However it is so buggy that there's no way we can run our
tests with it. And yes, we do mean "buggy" with the full force of that word. For
instance, the WebDriver specs specify that performing a click on an element
should scroll the element into view. Our tests rely on this, but Marionette does
not implement the scroll, which causes failures during testing.

Update Summer 2016: things are looking up. The Firefox developers have
been working on a driver named "Marionette" that *should* solve the
support problems. Stay tuned.

February 2016: For years, wed was supporting Firefox. Early on, Firefox was even
better supported than Chrome. However, the people responsible for maintaining
Selenium decided to stop supporting native events in Firefox and forced
developers to use synthetic events instead. The problem is that Selenium's
support for synthetic events on Firefox is unable to accurately reproduce what
happens when a user is actually interacting with a browser, *which is the entire
point of using Selenium in the first place*. The problem has been reported, at
length:

* In the `selenium-developers` group `here
  <https://groups.google.com/d/msg/selenium-developers/DKnG2lA-KxM/EMLiT87ykZYJ>`__ and in following replies.

* And these unresolved bugs `here
  <https://github.com/SeleniumHQ/selenium/issues/825>`__, and `here
  <https://github.com/SeleniumHQ/selenium/issues/1463>`__.

* And these resolved bugs `here
  <https://github.com/SeleniumHQ/selenium/issues/862>`__ and `here
  <https://github.com/SeleniumHQ/selenium/issues/813>`__.

It is taking forever for the problem to get resolved. In the meantime,
we have no resources to devote to solving the issue of synthetic event
support in Firefox and so Firefox support has been temporarily pulled.

IE11
----

We no longer support any version of IE. The benefit/cost ratio does not make it
viable for us to continue supporting IE. If **you** want to bring back support
for IE 11 you'll have to champion it: concretely, this means you need to provide
the development time to support it.

If somehow we were to reintroduce IE 11 support, we'd still be facing the
following issue. At some point in 2017 Selenium, IEDriver, or something else
changed in such a way that makes the test suite run incredibly slowly on
IE11. Wed itself runs at normal speed, as we can assess by running it manually
in IE11. We've looked for a solution but could not find one. Tracking down what
broke is more work than we can spend on this now. We accept bug reports due to
issues on IE11 and accept patches that would resolve the slowdown on IE11.

It is perhaps related to a bug whereby keystrokes are extremely slow in IE11,
but we've tried the solutions outlined there and nothing worked.

OS X
----

.. warning:: If you are using any version of OS X that hides
             scroll bars by default, you probably want to modify your
             OS X settings so that scroll bars are always
             shown. Otherwise, there are situations where you won't
             know about contents being scrollable. If you need help
             doing so, `see this blog post
             <http://heresthethingblog.com/2013/02/25/mac-tip-missing-scroll-bars/>`__. Note
             that wed will work either way, and you will be able to
             scroll either way, but wed relies on the traditional
             scroll bar behavior to indicate that something can be
             scrolled. So if you do not make the change above, you can
             end up in situations where something is scrollable
             without having any visual indication that *it is*.

The test suite depends on native events to do its work, but support
for native events in OS X is spotty:

* Chrome: it is possible to generate *some* native events.

* Firefox reports that it does not support native events at all.

* Safari does not support native events at all.

Your best bet in OS X is to use Chrome because we can't run the test
suite with Firefox or Safari.

Safari
------

Safari is a vexing case. Wed may or may not work on Safari. We currently cannot
run the automated test suite with Safari. Manual testing is out of the question.

We would like to have wed be supported on recent versions of Safari to the same
extent it is supported on recent versions of Chrome. The tool we use to test it
is Selenium. For better or for worse this is the go-to tool to do the kind of
test wed needs. We've not seen evidence of any collaboration between the
Selenium project and Apple. Thus testing support for Safari is deficient, and it
is not something that we here have the resources to fix.

If you desire that wed be actually tested on Safari and are in a position to
contribute substantial monetary or technical resources towards this goal, you
are welcome to contact us. In particular, immediate problem we've run into when
trying to test on Safari is this `Selenium issue
<http://code.google.com/p/selenium/issues/detail?id=4136>`__. If you want fix
it, then this would bring us one step closer to being able to test wed on
Safari. And regarding the state of Selenium support for Safari, take note this
response from a Selenium project member:

 Safari is not a priority, sorry. But your patches are welcome!

Absent these patches, wed is unlikely to support Safari.

.. _complex_name_patterns:

Complex Name Patterns
=====================

When you open the contextual menu to check what it is possible to insert in a
document you may see a menu item with an exclamation mark, labeled "Complex name
pattern". What's the deal?

Brief Explanation
-----------------

In brief, this occurs if the Relax NG schema uses a wildcard (so to speak) that
allows an unlimited number of possibilities for the name of an element or of an
attribute. (Or a set of possibilities that cannot be expressed as a set of
positive matches.)  Wed is able to validate such documents. However its
capability to edit them is currently limited. Wed will actually mark as **read
only** elements and attributes that are allowed only due to a wildcard. These
may not be modified in wed. The menu item that wed shows is a warning that the
schema allows for more than what wed is able to do. If this is a problem for
you, you should contact whoever provides you with technical support to discuss
the problem. You may direct them to read the explanation that follows.

Long Technical Explanation
--------------------------

A Relax NG schema normally constrains the set of possible valid structures to a
limited set. Take the following schema::

    start = element a { (element b { empty } | element c { empty })+ }

If we have finished reading the start tag for ``a``, then there are only two
possibilities: either a start tag for the element named ``b`` or a start tag for
the element named ``c``. However, Relax NG allows schemas that effectively say
"any element is fine here". For instance::

    start = element a { any+ }
    any = element * { any* }

The ``*`` that appears after the second ``element`` tells the validator that any
element name is possible. With this schema, once we've processed the start tag
for element ``a``, then it is possible to encounter any element whatsoever. This
is a problem for wed because, in addition to validation, it provides *guided*
editing.

For now, we've decided that wed will not support such patterns in editing. Why?
In our experience, these patterns are normally used to provide opportunities to
expand a schema. An excellent example is DocBook, which has provisions for
including XML structures encoded according to the MathML or SVG schemas. From
the standpoint of validating the document it makes good sense to have the
DocBook schema declare that some elements will allow any element, provided that
they come from the MathML or SVG namespaces. There are scenarios where it is not
necessary to know anything about MathML or SVG. This is fine insofar as
validation is concerned.

However, when *editing* to add a MathML section to a DocBook document, there's a
problem. Suppose a user wants to add a formula encoded with MathML to a DocBook
document, and user is using the default DocBook schema. The only thing wed has
to help the editing is "any element from MathML is valid here", because this is
what the default schema says. What are the consequences?

* First, wed is unable to check that the MathML is in fact *valid MathML*. The
  DocBook schema does not contain any information regarding what is valid
  MathML. It allows anything and everything, so long as it is declared to be in
  the MathML namespace. It therefore allows constructs that may not be valid
  MathML. (Note that wed is just following what the *schema specifies*, no more,
  no less.)

* Second, wed would have to prompt the user for every element and attribute
  name. For every MathML element to be added, the user would get a dialog box
  and have to enter an element's name, because wed has no finite set of options
  to choose from. Editing becomes a slog.

We've estimated that it is not worth adding to wed any facilities to support
scenarios like the one just described. If someone wants to edit DocBook
documents that allow MathML, they should provide wed with a DocBook schema that
has been merged with the MathML schema so that the final schema uses the actual
elements specified by MathML rather than say "anything from MathML is valid
here". This takes care of the problems mentioned above.

..  LocalWords: toolbars NG Ctrl tooltip autosave autosaves biblFull Minibuffer
..  LocalWords:  notesStmt TEI xml kbd ESC localStorage github Attr minibuffer
..  LocalWords:  ownerElement wed's prasāda abc subtype abcdef ap te ot DocBook
..  LocalWords:  MathML SVG autohiding Cmd Geckodriver WebDriver IEDriver kdb
