The gory details were that this form only got included from a DLL that had its conditional compilation directives wrong (for this build). However, this flash didn't occur in the Delphi 6 days. So I thought back to my previous experiences with PopupMode, and set PopupMode to pmAuto for this form and everything is great again.
Some days, I long for the Ctrl-S / Ctrl-Q days again.
Disclaimer The opinions expressed herein are my own personal opinions and do not represent my employer's view in any way.