No feature list you have to take on faith. Scrub, drag and click the pieces below. They run the same math the app does.
The frame behind ghosts warm, the frame ahead ghosts cool, the one you're on stays ink. The whole reason to draw the inbetween is to feel where it sits between the two keys. Scrub it and watch the spacing.
Fifteen presets: ink pens, pencils, charcoal, watercolor, a smudge that pushes paint around. A stabilizer for the long confident stroke. Make your own: the brush creator on the shelf mints presets, swaps tip and paper textures, and exports a brush as a .dbrush that unpacks whole on someone else's machine. Push the stabilizer and watch the wobble come out of the line.
Keys, holds and loops per layer. Expose on ones or twos, slide a key and everything downstream follows. The timing lives in the sheet, not buried in a curve editor. Click a cell to set or clear a key.
Pick on the wheel, read it as RGB or HSV, keep it in a managed palette that stays with the project. Export the whole model as a .dpal and the next film opens on the same colors. Drag the hue ring.
A project holds scenes, a scene holds cuts, a cut holds its own layers and length. Reorder them without renumbering anything by hand, and undo steps back through that structure, not just your strokes.
One .douga per project holds every scene, cut and layer. Out the other end: a PNG sequence, an animated GIF or APNG built right in, or an MP4, audio and all, if you point it at ffmpeg. The X‑sheet itself prints to PDF. Things come in, too: images, GIFs, footage to rotoscope, wav and mp3, pose packs.