How can I raise and focus a window if I don't have the window manager?

["godsatan" <godsatan kimo com tw>]

Dear Sirs,

I have three windows, main_window, mail_window, and mail_content_window.
This system is without window manger. I need show mail_window and let it
getting focus when user press a specific key on main_window. And then popup
a mail_content_window when user press enter key on mail_window. I use
gtk_widget_show() and gtk_window_activate_focus() to implement what i need.
The problem is only main_window and mail_window can get focus then get the
events. I couldn't switch focus from mail_content_window to mail_window
because it didn't get the focus. But mail_content_window is indeed showed.
Dose anyone can give me some advice about how to raise and focus a window if
I don't have the window manager?

Regards,
Calvin Chen