The dial

A collapsible radial control for Nijimi, based on the Surface Touch Paint vocabulary (spin, contract, expand, swap areas) and drawn at true phone scale.

Where this landed. The dial is not in the app. It was built to this spec, painted with, and dropped for a card of five colours across the bottom of the sheet. The reasoning is on Painting on a phone.

The four behaviours, and what each one solves here

Expand: Press and hold anywhere on the paper and the dial opens where your thumb already is, rather than at an edge your thumb has to travel to. Nothing has to be reached for.
Contract: Release and it is gone. The paper gets the whole screen back. Every layout so far has taken some of it, a row and a slider at a time.
Spin: This fixes what beat six earlier layouts: a direction holds seventeen to twenty-one colours and no row fits them. A ring shows eight at a time and spins to bring the rest round, so capacity stops being a function of screen width.
Swap areas: One control, several contents. Colour, brush and paper all use the same dial and the same movements, just a different ring.

It also answers the original complaint: inside the colour area, the angle picks the pigment and the distance from the centre picks the thickness. One thumb-down chooses both. Size stops being a separate control in a separate place for what the hand does as one action: picking up a loaded brush.

Try it

393 × 740 pt, true scale

Press and hold on the paper to open the dial. Keeping your finger down, move outward for a broader brush and around for a different pigment. Release to load it, then draw.

Drag inside the hub to spin the ring. That is how you reach the colours not currently facing you. Tap the hub without moving to swap the area.

The cost: a hold that has to mean "palette" without ever meaning "start a wet blot". In a paint app, pressing on the paper already has a job: it puts paint down. And everything past the first hold is learned rather than seen.

What it would replace

	On screen at rest	Colours reachable	Sizes	Acts to load a brush
Row + fan + edge slider	~115pt of row, plus the right edge	17–21	continuous	2
The dial	nothing	unlimited, because it spins	3 bands	1

The dial does not win on every row. Three thickness bands is fewer than a slider offers, and a hidden gesture is worse than a visible row for anyone opening the app for the first time. It wins on the two that have been the actual problem: it costs no screen, and its capacity does not depend on how wide the phone is.