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_grab_focus() instead of this function.
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_grab_focus() instead of this function.