WM_NCLBUTTONDBLCLK Overview  Group

The WM_NCLBUTTONDBLCLK message is posted when the user double-clicks 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_NCLBUTTONDBLCLK 

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

A window need not have the CS_DBLCLKS style to receive WM_NCLBUTTONDBLCLK messages.

Windows generates a WM_NCLBUTTONDBLCLK message when the user presses, releases, and again presses the left mouse button within the system’s double-click time limit. Double-clicking the left mouse button actually generates four messages: WM_NCLBUTTONDOWN, WM_NCLBUTTONUP, WM_NCLBUTTONDBLCLK, and WM_NCLBUTTONUP again.

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

See Also

DefWindowProc, MAKEPOINTS, POINTS, WM_NCHITTEST, WM_NCLBUTTONDOWN, WM_NCLBUTTONUP, WM_SYSCOMMAND 

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