An application sends the SBM_GETPOS message to retrieve the current position of the scroll box of a scroll bar control. The current position is a relative value that depends on the current scrolling range. For example, if the scrolling range is 0 through 100 and the scroll box is in the middle of the bar, the current position is 50.
SBM_GETPOS wParam = 0; // not used; must be zero lParam = 0; // not used; must be zero
This message has no parameters.
If the message succeeds, the return value is the current position of the scroll box in the scroll bar.