There are too many mistakes in this PR. (wrong class, duplicated code, unwanted synchronized code, many side effects that could break existing code, ...)

Also, as mentionned bt @crykn in the issue :

However, IIRC the consensus seems to have been to make the nestability optional, since checking the currently bound framebuffer isn't free and could negatively affect performance.

Requesting to reject it.

Hey, thanks for your feedback!

Maybe I misunderstood the need.

I now see as well that there's unnecessary synchronization.

Also, just to make sure that I'm not mistaking it again, the class to modify should be the base class GLFrameBuffer, not the regular FrameBuffer, right?

And finally, this feature shouldn't be forced... It should be optional, so a toggling method, maybe called setAutoRebind or something similar, should be available, right?

This seems to be something that should be handled externally in a util, rather than something that is baked deep into the framework internals. Much like how TextureBinder works, it is not enforced to be used.

NestedFrameBufferBinder {
begin(GLFramebuffer......)
end()

getCurrentBuffer()
getCurrentViewport

etc
}