An advanced visual editor for designing user interfaces.  Originally created by CooperAndPeters for VisualSmalltalkEnterprise, then ported to VisualAge.  Was purchased by ObjectShare, which was then gobbled up by ParcPlaceDigitalk, who then renamed themselves to Objectshare (you keeping up with this? <g>).

Active development moved to VisualAgeSmalltalk by EricClayberg at SmalltalkSystems.  Version 4.0 was a real winner.

See also InstantiationsInc, founded in 1997 by ObjectShare.  If you were lost by the history, try http://www.instantiations.com/VAST/more/history.html - you may become more confused.