In Gtk2, what's the difference between "active" and "focus"?

Spec开发者_如何学Cifically I'm interested in knowing what the difference is between a Gtk Window that has focus and one that is active.

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"Active" is a state (see the GtkStateType enumeration). A widget is always in exactly one state.

Having the focus means that the widget receives keyboard input, if any. Only one widget per top-level window can have the focus. Only widgets that actually can receive keyboard input are focusable, see the text for the gtk_widget_grab_focus(). I don't think that the actual window can have the focus.