Replace the bespoke colour pickers with the shared color_selector / color_list
widget so colour selection is identical everywhere:
- left properties panel (selected entities' colour)
- ribbon Home-tab colour dropdown
- layer manager per-layer colour
Each routes its "More…" entry to the standalone Select Color window via a
ColorPickTarget (Properties / Ribbon / Layer). Extracted color_list as the
shared popup content; the colour selector button now fills its container.
Co-Authored-By: Claude Opus 4.8 <[email protected]>