ComboBox creates a regular (non-modal) window; I believe this is fine.
A Dialog (modal window) can contain a ComboBox; I believe this is fine.
A non-modal child window of a modal window (e.g. a ComboBox pop-out within
a Dialog) wasn't clickable, and was blocked in the WindowManager.
I want to change this behavior.
This edge case occurs when trying to select a month in the "Calendar"
Application.