Causes widget to become the default widget. widget must be able to be
a default widget; typically you would ensure this yourself
by calling gtk_widget_set_can_default() with a TRUE value.
The default widget is activated when
the user presses Enter in a window. Default widgets must be
activatable, that is, gtk_widget_activate() should affect them. Note
that GtkEntry widgets require the "activates-default" property
set to TRUE before they activate the default widget when Enter
is pressed and the GtkEntry is focused.
Causes widget to become the default widget. widget must be able to be a default widget; typically you would ensure this yourself by calling gtk_widget_set_can_default() with a TRUE value. The default widget is activated when the user presses Enter in a window. Default widgets must be activatable, that is, gtk_widget_activate() should affect them. Note that GtkEntry widgets require the "activates-default" property set to TRUE before they activate the default widget when Enter is pressed and the GtkEntry is focused.