Automatically minimizing owned windows

["Engelen, J.B.C. (Johan)" <J B C Engelen ewi utwente nl>]

I am working on win32 (WinXP) and at the moment, dialogs that are made transient 
(gtk_window_set_transient_for) do not automatically minimize when the main window (their owner) is minimized. 
Does somebody know how this can be done?
Or is it possible to catch the minimizing event of the main window?

Regards,
Johan Engelen