Onion skin

Onion skin draws the neighboring frames on top of the one you are working on, so you can see the move.

The playback bar can show one to five previous frames, and one to five following frames. Onion Skin Settings opens the full panel.

Drawings ghosts the drawings themselves. Frames ghosts whole frames. Set how many previous and next ones to show, and link the two counts when they should stay equal.

Tinted colors the ghosts so previous and next are easy to tell apart. Original Colors leaves them as drawn. Each ghost has its own opacity.