Here are some various aspects that I’ve learned while using the Android app MidSequer:

• The screen scrolls fastest while selection-dragging if your grid is set to 8th notes.
• Many instruments allow multiple simultaneous notes on the same pitch. (Faux dynamics!)
• You can deselect selected notes if you redraw a box over the notes to deselect, and then pull the box out of them.
• Different phones even on the same Android version seem to play certain instruments differently, especially in the drum kit.