My screen is now off (presumably because of HiJacks screen blanking). I press a front panel button (not the top play/pause button) to wake it it.

Wait a minute. Now it sounds like you're complaining that the player software interprets your button press because you're using a button press to get out of the Hijack screen blanker.

That's not empeg's problem. The hijack screen blanker is a third-party product and is unrelated. Remember that the Hijack blanker is NOT SLEEP MODE, it's simply a screen saver. When you use a keypress to wake the screen-blanker, it passes that keypress on to the player software. This is completely intentional and by design. At this point, your complaint is about this behavior in hijack, not the behavior in the empeg software.

So if you use either the left-button or the right-button when the player has reached the end of a playlist, it starts playing. This IS DEFINITELY BY DESIGN, because it's more irritating to have to press "next track" followed by "unpause" to restart the playlist than it is to just press either of those buttons.

Now, if turning the volume knob makes it unpause from the "end of playlist" state (don't know if it does, haven't tried), I'm not sure if that's by design or not. Does it do that?