element.toBack([opt])
Move the element so it is behind all other cells (elements/links).
If opt.deep
is true
, all the embedded cells of this
element will get higher z
index than that of this element in a Breadth-first search (BFS) fashion. This
is especially useful in hierarchical diagrams where if you want to send an element to the back, you don't want
its children (embedded cells) to be hidden behind that element.