Hi Bruno,
though the problem persists, I have worked around it. I have noticed meanwhile that one or two other VCL-components have the same issue - perhaps it's not an issue after all? What I have done now is to capture the WM_NCLBUTTONUP and WM_NCLBUTTONDOWN messages of the form myself to handle my required behaviour. So this subject can be put to sleep.
Happy birthday BTW.
Cheers,
Jochem