The GetOpenClipboardWindow function retrieves the handle of the window that currently has the clipboard open.
HWND GetOpenClipboardWindow(VOID)
This function has no parameters.
If the function succeeds, the return value is the handle of the window that has the clipboard open. If no window has the clipboard open, the return value is NULL. To get extended error information, call GetLastError.
If an application or dynamic-link library (DLL) specifies a NULL window handle when calling the OpenClipboard function, the clipboard is opened but is not associated with a window. In such a case, GetOpenClipboardWindow returns NULL.
GetClipboardOwner, GetClipboardViewer, GetOpenClipboardWindow, OpenClipboard