[gtkada] Generating a handler for event of top window with gate

[Ludovic Brenta]

I've fixed the problem, it had to do with the merging.  Here is what I
had to do:

$ cp src/*.ad[bs] src/.gate/top_window
$ gate top_window.glade

The files under src/.gate2/top_window were the same as the ones in
src/.gate/top_window/tmp, so there were no differences to merge into
./src.

-- 
Ludovic Brenta.