I'm finding a little odd that people are having a problem with the R9 gpu.
I have a Radeon R9 380 and I have yet to have any issues with FL since I bought it and pretty much every GPU I have had has been a Radeon of some sort and I've never had problems with FL that I can recall.
I haven't installed the latest drivers as yet, but they have been downloaded.
I'm currently running the 17.2.1 software, the full package, not just the drivers.
EDIT: Updated to the very latest package for the R9 GPU, 17.4.3 and no problems. If anything FL looks a little more pretty than it did before.