This function should be called whenever keyboard navigation within
a single widget hits a boundary. The function emits the
"keynav-failed" signal on the widget and its return
value should be interpreted in a way similar to the return value of
Since 2.12
TRUE if stopping keyboard navigation is fine, FALSE if the emitting widget should try to handle the keyboard navigation attempt in its parent container(s).
This function should be called whenever keyboard navigation within a single widget hits a boundary. The function emits the "keynav-failed" signal on the widget and its return value should be interpreted in a way similar to the return value of Since 2.12