[0.4.12][COMCTL32] Fix regression CORE-16280

[0.4.12][COMCTL32] Fix regression CORE-16280

A very old regression. The visible symptom for us was, that the Apply button in our
desk.cpl was always visible, even in case no user input was done in the dlg yet.

I am still a bit afraid, because this patch is quite new and
it might unhide issues otherwhere, but since it fixes a regression,
I decided to take that risk.

This patch is a backport of 0.4.13-dev-908-g
344d5599351c5abae618dae9693a655cdc34dab0