When doing animations, it is very common :
-to use the same color palette again and again, with named colors to identify which goes where.
-have to replace a color with another. Doing it manually on each frame is very tedious, so a way to automate that would be very useful for animators.
Also, this could be useful to a smaller extent to single images.
Note that here we're talking about flat color areas without any anti-aliasing, so it should be "easily" possible to replace a color.
A possible way to include that feature could be:
-associate a palette to a file, so this palette would be automatically loaded in the palette selector for one document. People can still use other colors, but those will not be possible to replace automatically.
-add a few options in the palette docker to: display colors in a vertical list with their names next to it, add a way to name a color when adding a color to the palette, and add a way to replace an existing color while keeping its name.
-when user changes an existing color from the palette, all the areas in the document using this exact color will get replaced by the new color.