gtk_main problematic

[fjolliton free fr]

Hi!

I'm probably stupid, but I can't find how to handle correctly this
case:

I've a main widget displayed when program start, with a button than
open another window with it's own gtk_main loop (like a dialog box).
This last widget is made modal (either with gtk_widget_set_modal, or
with gtk_grab_add). (But this do not affect the behavior below, I
guess)

The problem: clicking window manager close button of the main window
terminate the gtk_main loop launched from the dialog box, then return
to "global" gtk_main loop.

What is the best solution to prevent this ?

I don't know any application that handle this possibility.. Nor gimp,
nor no-gtk app like Netscape, Knews,.. neither gnome-app like
gnome-terminal, and many (all?) other, close the entire app when we
close the main window even if a dialog is opened..

This is probably because it's better to do like this or because X
Window System can't provide this possibility ? (I known that
event-driven application under a graphical interface is very
complicated, because of all cases to handle. And GTK+ does too hack to
maintain a correct behavoir in most cases, according to me.)

(I hope you understand me. My english is very bad)