ptspointerpos (POINTS)
The pointer position is in window coordinates relative to the bottom-left corner of the window.
fsHitTestres (USHORT)
fsHitTestres provides the hit-test result. It contains the value returned from the hit-test process, which determines the window to be associated with this message. For details of the possible values, see WM_HITTEST.
fsflags (USHORT)
In addition to the control codes described with the WM_CHAR message, the following keyboard control codes are valid.
KC_NONE
rc (BOOL)
TRUE