@kas1e
Something else.
The game
Giddy 3 (old version) shows some black background flickering when playing using MiniGL4GL4ES.
Since the version available on OS4Depot is quite old i thought lets compile the more recent version of Giddy 3 and link it directly against GL4ES. Giddy 3 uses native AmigaOS4 code in order to draw to the screen (P96+MiniGL). I adjusted the OS4 render paths in order use OpenGL directly (like linux/pandora versions) so no more calls to P96+MiniGL.
The funny but bad thing: The new Giddy 3 build using GL4ES directly shows excactly the same rendering issues regarding black background flickering. I tried out almost all GL4ES environment variables but no luck so far.
And here is how it looks:

Maybe this is something where GL4ES can be improved. If you need the sources of new Giddy 3 or anything else let me know.