This message is sent to a window when the user double-clicks the left mouse button while the cursor is within a nonclient area of the window.
| Parameter | Description |
| wParam | Contains the code returned by WM_NCHITTEST (for more information, see the WM_NCHITTEST message, earlier in this chapter). | |
| lParam | Contains a POINT data structure that contains the x- and y-screen coordinates of the cursor position. These coordinates are always relative to the upper-left corner of the screen. |
If appropriate, WM_SYSCOMMAND messages are sent.