Suggestion to have a note in QClipboard under each function what is actually supported

"bool QClipboard::ownsClipboard () const" seems to always return false, and this is likely because it is not supported as said further up on the documentation page for QClipboard, "Windows and Mac OS X does not have the concept of ownership".

However there seems to be confusion among users what functions are supported and not. It would be nice if each function that was not supported on a given platform had a note in the documentation.