Add pick-up bar.
M1:

There's nothing stopping you from doing this now AFAIK, but I guess the MIDI playback would be wrong?
Of course we can add a pick-up bar, but the Beaming Pattern starts counting from the first note (instead of filling the pattern Backwards): in this example the single 1/8 note should be the first in the measure....
Also a Pick-up measure should be counted as measure 0 (zero) instead of measure 1.
I hope you'll understand what I mean though?
B.t.w. I didn't check the Midi-Player yet.
Yeah, it looks like we need an option to designate the first bar as a pickup bar (or just automatically detect if the first bar is incomplete).
MIDI playback would need to be adjusted similar to beaming so that the notes are played at the end of the measure rather than at the start.
PT1.7 handles this by detecting it. PT2 should as well.