[gtkada] Disabling Tree Collapse-Expand signal during double-click

[Wells, Larisa]

I am using a double click on a file tree node to spawn an editing session on
that file.  Does anyone know how I can effectively keep the tree node from
collapsing/expanding on a Gdk_2button_Press event?  I am accomplishing that
now by using Toggle_Expansion in my double-click callback, but the method is
kind of ugly and it flickers as it quickly expands and collapses.  I need to
keep the tree_expand and tree_collapse signal functionality for a selection
(single-click).