Double-click on expansion handle causes edit on bogus node in equation tree

[frothga]

The double-click seems to get interpreted twice, once to change expansion and again to initiate edit. However, the position where the edit is initiated and the node it is initiated on do not match, producing a horrific user experience.

One solution may be to simply not interpret double-click as edit. Alternately, filter the position so it only initiates edit if it is directly over a tree cell, rather than the expansion handle.