This class implements IUnknown and provides methods that enable a windowless control to receive window messages and to participate in drag-and-drop operations.
Your class, derived from IOleInPlaceObjectWindowlessImpl.
The IOleInPlaceObject interface manages the reactivation and deactivation of in-place controls and determines how much of the control should be visible. The IOleInPlaceObjectWindowless interface enables a windowless control to receive window messages and to participate in drag-and-drop operations. Class IOleInPlaceObjectWindowlessImpl provides a default implementation of IOleInPlaceObject and IOleInPlaceObjectWindowless and implements IUnknown by sending information to the dump device in debug builds.