This appears to be the same as XmClipboardStartCopy. This function allows you to try to copy the buffer that needs to be transferred to the clipboard. You can call this function just beforeXmClipboardRetrieve to figure out how much data is waiting. This way you can allocate storage dynamically. Copy a chunk of the clipboard's data into application memory.
Length indicates the buffer's size.
This function can return ClipboardLocked . This function creates temporary storage that will receive clipboard data. It must be called before any other XmClipboard operation. Widget is the widget ID receiving callbacks mentioned in callback. This function can return ClipboardLocked .