If focus is not the current focus widget, and is focusable,
sets it as the focus widget for the window. If focus is null,
unsets the focus widget for this window. To set the focus to a
particular widget in the toplevel, it is usually more convenient
to use gtk.widget.Widget.grabFocus instead of this function.
Sets the focus widget.
If focus is not the current focus widget, and is focusable, sets it as the focus widget for the window. If focus is null, unsets the focus widget for this window. To set the focus to a particular widget in the toplevel, it is usually more convenient to use gtk.widget.Widget.grabFocus instead of this function.