fine adjustments of freq with left and right arrows

Tried to add:
(void)keyDown:(NSEvent *)theEvent{...}

in WaterFall view but never called???

It's probably because the WaterfallView doesn't have the focus, and
the key press is not sent to it. I believe that the First Responder
needs to be set to the piece that you want to respond to the keyDown
event.

Is this a coding fix or a user behavior fix? I tried clicking on the Waterfall before I tried the <- -> keys. It did not help. It finds the mouseUp fine. But when I hit the left and right it rings the bell, (which sounds like the Focus error you mention).

This is a coding change. XTWaterfallView is not enabled to take
focus. I have to think on it and figure out which UI component really
should be the First Responder and react to the keyPress event. It
shouldn't be either XTWaterfallView nor XTPanadapterView because it
should respond whichever happens to be there. Probably it should be
the view of the entire main window that handles the event, this way
whenever the window has focus, you'll grab the keyPress event. The
way to do this is probably going to be to delegate the event to
somewhere else, maybe the main application object.

Also, if there is going to be a modifier key for 1 or 10 Hz
increments, it should not be option. I'm trying to reserve option for
"subreceiver" functions. So, if the arrow keys are implemented,
option-arrow should move the subreceiver frequency. Possibly shift is
the modifier key to use for the increment adjustments.

And maybe shift-option arrow could adjust the subreceiver.

Exactly.

Tried (a quick and dirty) to do this with buttons on MacHPSDR window. (linked in <- and -> arrows-keys to buttons.)

just did the following:
transceiver.frequency += 10;

This changes the frequency in the main Receiver window but does nothing for the real freq as heard nor as seen in the Panadaptor. Is there an update method/ Notification I should do for the PanAdaptor?

The fact that you're not hearing an audio change means that you're not calling [TransceiverController setFrequency:(int)theFrequency]. The text frequency display in the window is bound with cocoa bindings to the TransceiverController object in the NIB. The panadapter layer doesn't require any notification. It registers for notification on the transceiverController object (see the awakeFromNib method on XTPanAdapterView), and will automatically change if the frequency changes in TransceiverController.

(from [147]) Added rudimentary support for arrow key changing on the main window. This does not yet detect which key has changed, or implement modifier keys, but it is a start to the architecture. [#22]

(from [149]) Added the arrow key code from John James [#22]