[BUG] Changes to palette editor affect the wrong palette

[NicDoesCode]

When working with the Palette Editor, if you:

1. Select a colour on a palette
2. Click another pallette's header
3. Click that same colour and then change some value on the colour.

Changes are made to the same colour index on the previously selected palette, and not the current shown palette.

Changes should occur on the currently selected palette instead.