The WM_MOUSEACTIVATE message is sent when the cursor is in an inactive window and the user presses a mouse button. The parent window receives this message only if the child window passes it to the DefWindowProc function.
A window receives this message through its WindowProc function.
Syntax
WM_MOUSEACTIVATE WPARAM wParam LPARAM lParam;
Parameters
wParam Handle to the top-level parent window of the window being activated. lParam The low-order word specifies the hit-test value returned by the DefWindowProc function as a result of processing the WM_NCHITTEST message. For a list of hit-test values, see WM_NCHITTEST. The high-order word specifies the identifier of the mouse message generated when the user pressed a mouse button. The mouse message is either discarded or posted to the window, depending on the return value.
Return Value
The return value specifies whether the window should be activated and whether the identifier of the mouse message should be discarded. It must be one of the following values. MA_ACTIVATEActivates the window, and does not discard the mouse message.MA_ACTIVATEANDEATActivates the window, and discards the mouse message.MA_NOACTIVATEDoes not activate the window, and does not discard the mouse message.MA_NOACTIVATEANDEATDoes not activate the window, but discards the mouse message.
The return value specifies whether the window should be activated and whether the identifier of the mouse message should be discarded. It must be one of the following values.
Remarks
The DefWindowProc function passes the message to a child window's parent window before any processing occurs. The parent window determines whether to activate the child window. If it activates the child window, the parent window should return MA_NOACTIVATE or MA_NOACTIVATEANDEAT to prevent the system from processing the message further.
Notification Requirements
Minimum DLL Version NoneHeaderDeclared in Winuser.h, include Windows.hMinimum operating systems Windows 95, Windows NT 3.1
See Also
Mouse Input Overview, DefWindowProc, HIWORD, LOWORD, WM_NCHITTEST
WM_MOUSEACTIVATE = &H21Public Enum WM_MOUSEACTIVATE As Integer MA_ACTIVATE = 1 MA_ACTIVATEANDEAT = 2 MA_NOACTIVATE = 3 MA_NOACTIVATEANDEAT = 4End Enum