WM_NCLBUTTONUP message
Posted when the user releases 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.
A window receives this message through its WindowProc function.
#define WM_NCLBUTTONUP 0x00A2
Parameters
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wParam
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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.
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lParam
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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 value
If an application processes this message, it should return zero.
Remarks
The DefWindowProc function tests the specified 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.
You can also use the GET_X_LPARAM and GET_Y_LPARAM macros to extract the values of the x- and y- coordinates from lParam.
xPos = GET_X_LPARAM(lParam);
yPos = GET_Y_LPARAM(lParam);
Important
Do not use the LOWORD or HIWORD macros to extract the x- and y- coordinates of the cursor position because these macros return incorrect results on systems with multiple monitors. Systems with multiple monitors can have negative x- and y- coordinates, and LOWORD and HIWORD treat the coordinates as unsigned quantities.
If it is appropriate to do so, the system sends the WM_SYSCOMMAND message to the window.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client |
Windows 2000 Professional [desktop apps only] |
| Minimum supported server |
Windows 2000 Server [desktop apps only] |
| Header |
|
See also
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Reference
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Conceptual
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Other Resources