Trait containing all
Retrieves the current focused widget within the root.
Note that this is the widget that would have the focus
if the root is active; if the root is not focused then
gtk_widget_has_focus (widget) will be
false for the
the currently focused widget
If @focus is not the current focus widget, and is focusable, sets
it as the focus widget for the root.
If @focus is
None, unsets the focus widget for the root.
To set the focus to a particular widget in the root, it is usually
more convenient to use
WidgetExt::grab_focus() instead of
widget to be the new focus widget, or
to unset the focus widget