Superfluous/extra clefs and key signatures inserted after color change
-- Using MuseScore on Windows 10, versions 2.0.3 and 3 (185f329) --
MuseScore apparently has more serious problems with color manipulation than the inability to change the color of brackets (https://musescore.org/en/node/127131). In both 2.0.3 and 3 nightly, when you change the color of clefs or key signatures the program adds in unnecessary new clefs and key signatures "downstream" from the recolored items.
For example, here are a few bars before recoloring the system's clef and key signature:
and here are the same bars after applying a new color to the clef and key signature at the left side of the system. MuseScore has inserted new, redundant clef and key signature items in the middle of the line (they're the right color, anyway):
Note that in the second example I've also changed the colors of the notes, rests, barlines and staff lines, but those changes didn't cause extra items to appear. (You can tell from the picture that this is 2.x, because the ledger lines don't change color when you change the color of the staff lines. That bug has been fixed in 3.)
It may or may not be relevant to mention that I went back to version 1.3 and tried recoloring clefs and key signatures there. It worked fine--no extra markings were added. But when I opened the 1.3 file in 2.0.3, now every staff on every system had an unnecessary extra clef and key signature.