void gtk_window_set_type_hint ( GtkWindow* window, GdkWindowTypeHint hint )
By setting the type hint for the window, you allow the window manager to decorate and handle the window in a way which is suitable to the function of the window in your application.
This function should be called before the window becomes visible.
gtk_dialog_new_with_buttons() and other convenience functions in GTK+
will sometimes call
gtk_window_set_type_hint() on your behalf.
The window type.