Once tried to do something like this on FMX, 1. Could not get it to look right 2. Was so much work.
Memory of the process is very vague, tried to make some style thingy and use that.
My observation was so that some things on Fmx are very complicated. Easier to make style than totally new VCL component with similar support build in, maybe. it depends I guess.
Should give fmx a new change, do simple project with it.
-Tee-