Palette Editor Panel
From Synfig Studio :: Documentation

Here you can add, edit or delete your preferred colors from your document. A right click on a color gives you 2 options: color (to edit the color) and delete (to delete it).
The buttons at the bottom of the panel allow you to add a new color, save the current palette in Synfig Palette format (.spal), load a palette in Synfig Palette format (.spal), or reset the current palette colors, discarding any change you've done.
Support for loading a GIMP palette will soon be available, and can meanwhile be achieved with an external script converting GIMP palettes (.gpl) into Synfig palettes (.spal): Doc:GIMP palette converter.