I am not a programmer, I can not do this. I wonder why these icons have been choosen. They are almost impossible to see.
Is there a possibility to use another editor within XF, which has icons that the user actually can see?
Doesn't involve being a programmer, but someone that is not graphically challenged (unlike me!). You have already been pointed towards a great one by @Shelley - she is NOT graphically challenged as you can see.
You can also edit the colors of the editor icon box in the ACP to style it to be a lighter or darker.