Modeling focus change as an operation is awkward, because focus changes
logically happen during event processing, not layout. In particular, you
want to apply focus changes even if a widget is subsequently never laid
out.
Now that input.Source is concrete, it's much more straightforward to
offer focus changes as a command which can be queued through the
Source. A future change may similarly offer a command for directional
focus changes.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
This change gets rid of the event.Queue interface by replacing it with
input.Source values. Source provides the interface to Router necessary
to implement interface widgets.
Signed-off-by: Elias Naur <mail@eliasnaur.com>