WM_SIZECLIPBOARD    
The
WM_SIZECLIPBOARD message is sent to the clipboard owner by a clipboard viewer
window when the clipboard contains data in the CF_OWNERDISPLAY format and the
clipboard viewer s client area has changed size. 
WM_SIZECLIPBOARD 
hwndViewer = (HWND) wParam;  // handle of clipboard viewer window 
hglbRc = (HGLOBAL) lParam;   // handle of RECT object 
 
Parameters
hwndViewer
Value of wParam.
Identifies the clipboard viewer window. 
hglbRc
Value of lParam.
Identifies a global memory object that contains a RECT structure. The structure
specifies the new dimensions of the clipboard viewer s client area.
Remarks
When the
clipboard viewer window is about to be destroyed or resized, a WM_SIZECLIPBOARD
message is sent with a null rectangle (0, 0, 0, 0) as the new size. This
permits the clipboard owner to free its display resources. 
The clipboard
owner must use the GlobalLock function to lock the memory object that
contains RECT. Before returning, the clipboard owner must unlock the
object by using the GlobalUnlock function. 
See Also