WM_NULL message
Applies to: desktop apps only
Performs no operation. An application sends the WM_NULL message if it wants to post a message that the recipient window will ignore.
A window receives this message through its WindowProc function.
#define WM_NULL 0x0000
Parameters
- wParam
-
This parameter is not used.
- lParam
-
This parameter is not used.
Return value
Type: LRESULT
An application returns zero if it processes this message.
Remarks
For example, if an application has installed a WH_GETMESSAGE hook and wants to prevent a message from being processed, the GetMsgProc callback function can change the message number to WM_NULL so the recipient will ignore it.
As another example, an application can check if a window is responding to messages by sending the WM_NULL message with the SendMessageTimeout function.
Requirements
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Minimum supported client | Windows 2000 Professional |
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Minimum supported server | Windows 2000 Server |
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Header |
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See also
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Build date: 2/3/2012
