Index: /CKEditor/branches/prototype/_source/core/env.js
===================================================================
--- /CKEditor/branches/prototype/_source/core/env.js	(revision 2339)
+++ /CKEditor/branches/prototype/_source/core/env.js	(revision 2340)
@@ -106,9 +106,16 @@
 			// Internet Explorer 6.0+
 			if ( env.ie )
-				return ( agent.match(/msie (\d+)/)[1] >= 6 );
+				return ( agent.match( /msie (\d+)/ )[1] >= 6 );
 
 			// Gecko.
 			if ( env.gecko )
-				return navigator.productSub >= 20030210;
+			{
+				var geckoRelease = agent.match( /rv:((?:\d|\.)+)/ );
+				if ( !geckoRelease )
+					return false;
+				geckoRelease = geckoRelease[1].split( '.' );
+				geckoRelease = geckoRelease[0] * 10000 + ( geckoRelease[1] || 0 ) * 100 + ( geckoRelease[2] || 0 );
+				return geckoRelease >= 10801;
+			}
 
 			// Opera 9.50+