The WM_HSCROLLCLIPBOARD message is sent to the clipboard owner by a clipboard viewer window. This occurs when the clipboard contains data in the CF_OWNERDISPLAY format and an event occurs in the clipboard viewer’s horizontal scroll bar. The owner should scroll the clipboard image and update the scroll bar values.
WM_HSCROLLCLIPBOARD hwndViewer = (HWND) wParam; // handle of clipboard viewer window nScrollCode = (int) LOWORD(lParam); // scroll bar code nPos = (int) HIWORD(lParam); // scroll box position
| Value | Meaning | 
| SB_BOTTOM | Scroll to lower right. | 
| SB_ENDSCROLL | End scroll. | 
| SB_LINEDOWN | Scroll one line down. | 
| SB_LINEUP | Scroll one line up. | 
| SB_PAGEDOWN | Scroll one page down. | 
| SB_PAGEUP | Scroll one page up. | 
| SB_THUMBPOSITION | Scroll to absolute position. The current position is specified by the nPos parameter. | 
| SB_TOP | Scroll to upper left. | 
If an application processes this message, it should return zero.
The clipboard owner can use the ScrollWindow function to scroll the image in the clipboard viewer window and invalidate the appropriate region.