grab focus

[Du Jun <engp8815 nus edu sg>]

Hi,
I want to grab a focus to a sepecial window. But I have tried
gtk_window_set_focus, gdk_keyboard_grab(). but it seems no use at all.
what should I do? And how can I detect the previous focused window ID so
that I can send keyboard event that I don't need back to the window?
Thank you
Sincerely
Du