I, too, have been trying to set my monitors’ gamma to 2.2 lately. I agree that QT player uses ColorSync, no problems there.
However as far as I could find (by trying and searching the manual), there is no way to prevent FCP from “correcting” the gamma. This is what I found in the FCP 6 manual:
‘Whenever you watch your video on a computer display (such as video displayed in the Canvas, the Viewer, or via Digital Cinema Desktop Preview), Final Cut Pro applies gamma correction to the video to more closely approximate the way it would appear on a video monitor.
Note: Gamma correction is not applied to external video outputs such as DV or third-party interfaces because this correction is inherently applied by external video monitors.‘
For still images and RGB video codecs there is an option to set the source gamma, but (quote) ‘Y