Ah, sorry for my bad English.
My question is not how to get instance variables in event sheet.
My question is how to get instance variables' name(in engine, the name will be transfered to an index) in plugin, like the condition : "Compare instance variable" does.
<img src="http://i1081.photobucket.com/albums/j352/rexrainbow1/getpvofinst.png" border="0" />
More precise, how to get the combox input to select instance variablies in plugin.