Small but reproducible quirk/bug in Pyxel Edit...
1. Click + to add a new colour to the palette
2. Double-click the new colour. Note the new colour is selected.
3. Adjust any slider (e.g. the L one) in the 'Adjust palette swatch' dialog.
The third step deselects the new colour and selects the previous one. The wrong colour is still selected if you click OK or Cancel.
(An aside: Enjoying Pyxel Edit so far, though I am missing a random fill tool (see TileStudio) and I've experienced a couple of strange inconsistent bugs I haven't figured out yet. Will post if/when I do.)
This was experienced using the AIR version, pyxel version 0.3.106, on Windows 8.1.