::keynav-failed signal on the widget.
This function should be called whenever keyboard navigation within a single widget hits a boundary.
The return value of this function should be interpreted
in a way similar to the return value of
TRUE is returned,
stay in the widget, the failed keyboard navigation is OK
and/or there is nowhere we can/should move the focus to.
FALSE is returned, the caller should continue with
keyboard navigation outside the widget, e.g. by calling
gtk_widget_child_focus() on the widget’s toplevel.
GtkWidget::keynav-failed handler returns
For the other values of
GtkDirectionType it returns
Whenever the default handler returns
TRUE, it also calls
gtk_widget_error_bell() to notify the user of the
failed keyboard navigation.
A use case for providing an own implementation of ::keynav-failed
(either by connecting to it or by overriding it) would be a row of
GtkEntry widgets where the user should be able to navigate
the entire row with the cursor keys, as e.g. known from user
interfaces that require entering license keys.
Direction of focus movement.