Glade pygtk show and hide problem

Hi all!
I have made my GUI in Glade 3 with a couple of windows.
When I click a button a window should show:

my_window.show()

That works fine.
If I close my window with:

my_window.hide()

The next time I show the window it works fine, but if I close my window with the X up in right corner the next time I try to open my window I get an error:
GtkWarning: gtk_container_foreach: assertion 'GTK_IS_CONTAINER (container)' failed.
I suppose that a destroy command is issued when I do that.
But how do I prevent this from happening?
I have tried to set hide in destroy event on window but this does not work.
Destroy must happen after my hide command, right?
Please help!
Many thanks!