WM_NCMOUSEMOVE
nHittest = (INT) wParam; /* hit-test code */
pts = MAKEPOINTS(lParam); /* mouse-cursor coordinates */
The WM_NCMOUSEMOVE message is posted to a window when the mouse cursor is moved within the nonclient area of the window. This message is posted to the window that contains the mouse cursor. If a window has the mouse captured, this message is not posted.
nHittest
Value of wParam. Specifies the hit-test code returned by the DefWindowProc function as a result of processing the WM_NCHITTEST message. For more information, see the description of the WM_NCHITTEST message.
pts
Value of lParam. Specifies a POINTS structure that contains the x- and y-coordinates of the mouse cursor. The coordinates are relative to the upper-left corner of the screen. The POINTS structure has the following form:
typedef struct tagPOINTS { /* pts */
SHORT x;
SHORT y;
} POINTS;
An application should return zero if it processes this message.
If appropriate, WM_SYSCOMMAND messages are sent.
The MAKEPOINTS macro can be used to convert the lParam parameter to a POINTS structure.
DefWindowProc, WM_NCHITTEST