When I attempt to invert the screen, I get Output 50: gamma_control::Event::Failed. Seems like it might be a hardware thing, since Picom under X also complains (error 160 GLX_BAD_DRAWABLE request 152 minor 29 ) - I don't think this is a problem with ws-gammarelay-rs.

All of the controls except invert work, until we try to invert, then nothing works.

When zwlr_gamma_control_v1::Event::Failed is received, we destroy the output (lines 191-194). The documentation states that the control is no longer valid, but makes no statement about the output, so maybe destroying the output is not the correct behavior.

Since everything (except invert) works until the output is destroyed, so maybe we should just recreate the control (though having tried this, it didn't work -- not sure if this is a problem with my implementation), or maybe it's ok to ignore this and accept it as a limitation of wl-gammarelay-rs that you cannot try to manipulate gamma in an unsupported way.

So in the end maybe this is more of a question than a bug report !