NAME
	OpenClipboard -- create a handle on a clipboard unit. (V36)

   SYNOPSIS
	ch = OpenClipboard(unitNumber)
	D0                 D0

	struct ClipboardHandle *OpenClipboard(LONG);

   FUNCTION
	Opens the clipboard.device and opens a stream for the specified unit
	(usually PRIMARY_CLIP). This handle structure will be used as the
	clipboard stream for IFFHandles initialized as clipboard streams by
	InitIFFasClip().

   INPUTS
	unitNumber - clipboard unit number (usually PRIMARY_CLIP).

   RESULT
	ch - pointer to ClipboardHandle structure or NULL if unsuccessful.

   BUGS
	This function had several bugs prior to V39.

       First bug was that if the clipboard.device couldn't open, two calls
	to FreeSignal() were made with uninitialized values as parameters.
	The result of this was a corrupt signal mask in the Task field.

	Second bug was that OpenDevice() was called with an IO request that
	didn't have a valid MsgPort pointer in it.

	Third bug was that the two message ports allocated by the function
	(ClipboardHandle->cbh_CBport and ClipboardHandle->cbh_SatisfyPort)
	were not being initialized correctly and would cause a system crash
	if a message ever got to either of them.

   SEE ALSO
	InitIFFasClip(), CloseClipboard(), <libraries/iffparse.h>