SETCAPTUREWindows API Call in RapidQ2.INCWindows

Windows API that sets the mouse capture to the specified window belonging to the current program. Once a window has captured the mouse, all mouse input is directed to that window, regardless of whether the cursor is within the borders of that window. Only one window at a time can capture the mouse. This is a keyword in RAPIDQ2.INC

SyntaxHandle = SETCAPTURE(hWnd)
DIM aHandle AS LONG
aHandle = SETCAPTURE(Canvas.Handle)

Details:
If the function succeeds, the return value is the handle of the window that had previously captured the mouse. If there is no such window, the return value is NULL. See RELEASECAPTURE and GETCAPTURE