Geoff Chappell - Software Analyst
The IWinEventHandler methods are (as ordered in the virtual function table after the IUnknown methods):
HRESULT OnWinEvent (HWND, UINT, WPARAM, LPARAM, LRESULT *);
HRESULT IsWindowOwner (HWND);
In Windows Vista, implementations of the IWinEventHandler interface are known in the following executables: BROWSEUI, COMDLG32, EXPLORER, IEFRAME, MSOE, SHDOCVW and SHELL32.
The IWinEventHandler interface first appears in SHDOCVW.DLL version 4.71 and EXPLORER.EXE version 4.71. Classification, between the Windows shell and Internet Explorer, is uncertain. The interface is not even known to SHELL32.DLL until version 5.00.
Though this interface dates from as long ago as 1997, it is still not documented by Microsoft as late as the January 2007 edition of the Windows Software Development Kit (SDK).