I actually have this bit of code in my Cairo patch as well (but not being used at the moment), which I most likely took from DT some years ago… however, in this case one needs a mechanism for telling Cairo which monitorID to use, and ideally one would want to set this individually for each drawing context (because you might have an application with multiple windows scattered across multiple displays, and you want each window to be properly color managed). That most likely involves some API changes, while the “simple” solution, valid for the main display only, works with the current API. Maybe we should proceed step-by-step…