I would say - rely on qt5 rendering and don't go lowlevel into drivers. If driver is buggy then mention that (or better bugreport into mesa.org/freedesktop.org bugtracker) and do not workaround. intel, nouveau, radeon drivers on linux are maintained, so should get bugfixes after that.

Doesn't qt5 give enough crossplatform to do not care (much) whether we are on windows/mac or linux? Some crossplatform build system (cmake.org prehaps)