The Clipboard owner's OnRenderFormat member function is called by the framework when a particular format with delayed rendering needs to be rendered.
The receiver should render the data in that format and pass it to the Clipboard by calling the SetClipboardData Windows function.
Do not call the OpenClipboard member function or the CloseClipboard Windows function from within OnRenderFormat.
This member function is called by the framework to allow your application to handle a Windows message. The parameters passed to your function reflect the parameters received by the framework when the message was received. If you call the base-class implementation of this function, that implementation will use the parameters originally passed with the message and not the parameters you supply to the function.