WM_NCLBUTTONDOWN

The WM_NCLBUTTONDOWN message is posted when the user presses the left mouse button while the cursor is within the nonclient area of a window. This message is posted to the window that contains the cursor. If a window has captured the mouse, this message is not posted.

WM_NCLBUTTONDOWN 
nHittest = (INT) wParam;    // hit-test value 
pts = MAKEPOINTS(lParam);   // position of cursor 
 

Parameters

nHittest

Value of wParam. 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.

pts

Value of lParam. Specifies a POINTS structure that contains the x- and y-coordinates of the cursor. The coordinates are relative to the upper-left corner of the screen.

Return Values

If an application processes this message, it should return zero.

Default Action

The DefWindowProc function tests the given point to find out the location of the cursor and performs the appropriate action. If appropriate, DefWindowProc sends the WM_SYSCOMMAND message to the window.

Remarks

An application can use the MAKEPOINTS macro to convert the lParam parameter to a POINTS structure.

QuickInfo

  Windows NT: Requires version 3.1 or later.
  Windows: Requires Windows 95 or later.
  Windows CE: Unsupported.
  Header: Declared in winuser.h.

See Also

Mouse Input Overview, Mouse Input Messages, DefWindowProc, MAKEPOINTS, POINTS, WM_NCHITTEST, WM_NCLBUTTONDBLCLK, WM_NCLBUTTONUP, WM_SYSCOMMAND