Click in the open space to **add a node**, drag from one node to another to **add an edge**.  
Ctrl-drag a node to **move** the graph layout.  
Click a node or an edge to **select** it.

When a node is selected: **R** toggles reflexivity, **Delete** removes the node.  
When an edge is selected: **L**(eft), **R**(ight), **B**(oth) change direction, **Delete** removes the edge.

To see this example as part of a larger project, check out [Modal Logic Playground](http://rkirsling.github.com/modallogic/)!