void gtk_window_set_focus ( GtkWindow* window, GtkWidget* focus )
Sets the focus widget.
focus is not the current focus widget, and is focusable,
sets it as the focus widget for the window. If
unsets the focus widget for this window. To set the focus to a
particular widget in the toplevel, it is usually more convenient
gtk_widget_grab_focus() instead of this function.
Widget to be the new focus widget, or
NULLto unset any focus widget for the toplevel window.
The argument can be
The data is owned by the caller of the function.