Don't remove the GDK_KEY_space in GimpSearchPopup because that's
impossible and removes it from the entire GimpPopup class. Instead,
don't handle the "space -> confirm" binding manually if the focus
widget is a text widget.
Based on GimpPopup as parent, this is a generic search popup widget,
which can display any list of action. The results construction logics
is not part of the widget, and is built through a callback instead,
which could allow to use it to create different dialogs.
luz.paz