Jason Persampieri wrote:

> And beware calling your 'draw_display' from initialize now.  The widget
> will be created in the first pass, then throw an error in the second pass (when it tries to create
> it again).

Actually, it's the other way around. If you put the call to @tree.create 
in your 'draw_display' method and then call draw_display directly from 
MainWindow#initialize, the sequence of events is:

  1. MainWindow#initialize instantiates (but does not
     create) a number of widgets, then calls draw_display.

  2. MainWindow#draw_display instantiates the tree list
     (@tree) and tries to call create() on it. This fails
     because you have not yet called FXApp#create.

-- Lyle