Wow! A very minor yet critical tweak - this editor used to run very slow, and had to redraw the grid whenever you scroll. Just by pre-drawing the interface and using GCOPY instead, it runs WAY faster! To the extent at which I had to make it scroll only every 3 frames a button is held to still allow some precision and avoid graphical glitches! xD

key?

This is still very much work in progress. I haven't even added note placing yet!