Info request re dialog boxes

[John Iliffe <john iliffe sympatico ca>]

I am experimenting with GTK trying to learn how to build an application
and have built a test application that uses a number of dialog boxes in
a series: 
 
eg:
1 - "your file is missing" (requires a click on the "OK" button)
2 - "do you want to create a new file" (requires a two button yes/no
selection)
3 - etc...

What happens is that the program "falls through" and instead of stopping
until the user clicks a button, I get a stack of dialog boxes one on top
of the other and they each have to be clicked off separately.  What's
worse, it is in reverse order so the request for a solution occurs
before the info re what's wrong. 

The dialog boxes are modal (gtk_grab_add) and the buttons have defaults
(gtk_widget_grab_default).  The event handlers attached to each one work
correctly, that is when you finally get to click the button the correct
handler executes. 

The dialog boxes are not in the main window container (to catch
gtk_main() ) since I get a run time crash and core dump if I try to do a
gtk_container_add on the main window container. (compiles OK).

This is probably fairly obvious but it sure has me stymied! Help
appreciated.

Thanks.

John