CComControlBase::m_bWasOnceWindowless
Flag indicating the control has been windowless, but may or may not be windowless now.
unsigned m_bWasOnceWindowless:1;
Remarks
Note
To use this data member within your control class, you must declare it as a data member in your control class. Your control class will not inherit this data member from the base class because it is declared within a union in the base class.
Requirements
Header: atlctl.h