GtkWindow::set_default
Sets default_widget as the default widget for the window. The default widget is the widget that will receive focus when the window receives focus.
If null is passed as default_widget, the default widget will be unset.
It is normally easier to call grab_focus() on the widget that you want to make the default rather than using set_default() .
Before you can set a widget as the default you must set the
Gtk::CAN_DEFAULT flag for the widget by calling
set_flags.
See also: activate_default() grab_focus() set_flags