[pygtk] Problem with window.set_modal()

[Mauro Giacomini]

Hello to all.
I have a problem with the set_modal function in a pygtk program I'm writing.
The situation:
I have a main window; when the user clicks on a button, a new window 
came up for the selection of a particular item in a treeview.
When the user confirm the selection with the click on the "ok button", 
this window disappear (destroy) and the interaction return to the main 
window.
But, although I declare the second window such as modal window and 
transient for main window, the instruction I put in the main window 
after the call to the second window are executed without waiting the 
response for the second window.
Is there something else to do?
Or is there a better approach to a similar situation?

Mauro

PS: Sorry for my english, but I'm an Italian guy.