A small quirk I ran into:

Suppose you have entered some notes like shown in the screenshot. You'll hear two clean bleeps when you play it. If you select the highlighted point and enter '1', you'll hear the slide effect when playing the sound again, but it will not be visible. I'd either expect it to be visible in the UI or to have no effect on the sound.

Ah, I think this has happened to me before. Two patterns that looked the same sounded different…

I didn't understand what you were describing at first, but I think I see now.

Putting a '1' in the effect column for that row /does/ turn on the slide modifier (as expected), but it does not remain visible in the tracker.

Yeah, definitely a bug.