Done! xD, a new version has that feature implemented, wait for Firefox to update it and you'll be able to enjoy it, or install it again to force update. Thank you for your suggestion!

Edit:
strange about the addendum2, I tried replicating it but I wasn't able to get the color problem you got. Would you be kind enough to open an issue on github repo (https://github.com/2alin/tabFx/issues) and attach some pictures (or video) of it?.
If you do, I promise I'll dedicate time and effort to find the reason of the issue you are having with this addon and others.

Edit 2:
problem fixed since v1.2