Rated 5 out of 5 stars

Great add-on. Couple suggestions when time permits:
1. Reduce size of sample color bars in options (show more per screen)
2. Right-click "Mark!" for options. This would be a quick way to change colors.
3. Better yet...allow maybe 5 favorite colors to be chosen in options, then show these colors in drop-down on right-click of Mark! icon.

This add-on has some real potential and I'm so glad the author created this.

This review is for a previous version of the add-on (3.2).  This user has other reviews of this add-on.

I'm already testing a solution for quick colour change.
(Right-click "Mark!" button is currently not possible beause this opens Thunderbird's customising menu, but pressing Ctrl + click on "Mark!" button is working.)