CheckMsgFilterHook - Remarks

This hook enables an application to apply a very specific message filtering, for example, based on the values of message parameters.

This hook is called after window handle filtering and before message filtering. Window handle filtering is controlled by the hwndFilter parameter of the WinGetMsg or WinPeekMsg functions. Message filtering is controlled by the ulFirst and ulLast parameters of the WinGetMsg, WinPeekMsg or WinWaitMsg functions.

This hook is called if the message passes window handle filtering and if non-null message filtering is specified. This means that, on entry to this hook:

• The hwndFilter parameter of the WinGetMsg or WinPeekMsg function is either NULLHANDLE or it specifies the window (or a parent of the window) referenced in the pQmsg structure.

• At least one of the usFirst and usLast parameters are nonzero.

• The field of the pQmsg structure might or might not lie inside the range specified by the usFirst and usLast parameters.