More info: some of my projects are affected, others are not. I haven't found any common ground yet. Unfortunately the one I have right now I cannot publish, I'll try to derive a smaller version and strip it down as far as possible and then post it here.
With the most simple "Hello World" GUI program, 1 form, 1 button, 1 messagebox, freshly created on the Mac, the problem does not arise.
Finding this by comparing project files and options could take quite some time ... almost indefinite possibilities ... any hint from a compiler guru where to start looking would be a great time and nerve saver.
Armin.