Now another problem:
VertexChameleon works as usual (deleted "-borderStyle" in all scripts, changed "polygons" into "modeling"),
but only with 2 colors.
At first, only blue and magenta.
Then I deinstalled and did all again, in case I accidentally changed a script.
Now, it is just green and yellow.
I can apply all colors as usual via the maya paint vertex color tool.
Only chameleon would deal with two!