Index: src/core.js
===================================================================
--- src/core.js	(r�vision 5772)
+++ src/core.js	(copie de travail)
@@ -614,8 +614,11 @@
 
 	// See test/unit/core.js for details concerning this function.
 	isFunction: function( fn ) {
-		return !!fn && typeof fn != "string" && !fn.nodeName &&
-			fn.constructor != Array && /^[\s[]?function/.test( fn + "" );
+		return !!fn && typeof fn != "string" && !fn.nodeName 
+			&& fn.constructor != Array 
+			&& ( typeof fn.prototype == "object" 
+				|| typeof fn.prototype == "function" 
+				|| (''+fn).indexOf('[native code]') >= 0 );
 	},
 
 	// check if an element is in a (or is an) XML document