NAME
	GetVPModeID -- get the 32 bit DisplayID from a  ViewPort. (V36)

   SYNOPSIS
	modeID =  GetVPModeID( vp )
	d0		       a0

	 ULONG GetVPModeID( struct  ViewPort *);

   FUNCTION
	returns the normal display modeID, if one is currently  associated 
	with this  ViewPort.

   INPUTS
	vp -- pointer to a  ViewPort structure.

   RESULT
	
	modeID -- a 32 bit DisplayInfoRecord identifier associated with 
		  this  ViewPort, or INVALID_ID.

   NOTES
	Test the return value of this function against INVALID_ID, not NULL.
	(INVALID_ID is defined in  sc:include/graphics/displayinfo.h).

   BUGS

   SEE ALSO
	 sc:include/graphics/displayinfo.h,  ModeNotAvailable()