One more thing. Are you aware that in recent releases the official supported solution is SuggestedValues? Assuming you restrict what users can input by input help it is similar to history although more entries will be displayed (instead of only those the user has input before).
http://help.sap.com/saphelp_nw73ehp1/helpdata/en/18/d09132a1b67246987b4b12063151b4/frameset.htm