Thanks for the reply! So it's not just me!
I actually made a set of styled components for Delphi 20 years ago but they didn't easily translate to fpc/Laz.
So delighted to find something fairly similar.
What I want to build now is a tool to create styles where the colour palette (hue) is shifted, say, 180degrees or 120 degrees, and all other properties the same.
Not sure whether trying to solve the bug myself is the best way forward OR hard code (as you suggested) all the individual properties.