You cannot custom color a header, but in some cases you can replace a header with an axis on which you put the dimension as the label. You can then use the color shelf of this axis to custom color the dimension value.
In the attached, I created an axis with a constant negative value. I added this axis on the rows, using Dual Axis - Synchronise Axis. This gives me a mark in the negative zone.
I can then put the region on the Label shelf of this axis , and the color logic on the Color shelf.
I also need to hide the real Region header by right-clicking on the Region blue pill and unselecting Show Header
Book3.twbx 1.2 MB
Great idea, I'll give this a try - thank you!!!