Causes this to have the keyboard focus for the `GtkWindow` it's inside.
If this is not focusable, or its [[email protected]_focus] implementation cannot transfer the focus to a descendant of this that is focusable, it will not take focus and false will be returned.
Calling [[email protected]_focus] on an already focused widget is allowed, should not have an effect, and return true.
this |
a `GtkWidget` |
true if focus is now inside this. |