Widget: Added ability to use $.widget() to create extensions. Fixes #…

…6937 - Widget: Allow redefining a widget to create extensions.

tests/unit/widget/widget_core.js

@@ -821,4 +821,25 @@ test( "auto-destroy - .detach()", function() {
 	$( "#widget" ).testWidget().detach();
 });
 
+test( "redefine", function() {
+	expect( 4 );
+	$.widget( "ui.testWidget", {
+		method: function( str ) {
+			strictEqual( this, instance, "original invoked with correct this" );
+			equal( str, "bar", "original invoked with correct parameter" );
+		}
+	});
+	var ctor = $.ui.testWidget;
+	$.widget( "ui.testWidget", $.ui.testWidget, {
+		method: function( str ) {
+			equal( str, "foo", "new invoked with correct parameter" );
+			this._super( "method", "bar" );
+		}
+	});
+
+	var instance = new $.ui.testWidget();
+	instance.method( "foo" );
+	equal( $.ui.testWidget, ctor, "constructor did not change" );
+});
+
 }( jQuery ) );

ui/jquery.ui.widget.js

@@ -36,7 +36,7 @@ $.widget = function( name, base, prototype ) {
 	};
 
 	$[ namespace ] = $[ namespace ] || {};
-	$[ namespace ][ name ] = function( options, element ) {
+	$[ namespace ][ name ] = $[ namespace ][ name ] || function( options, element ) {
 		// allow instantiation without "new" keyword
 		if ( !this._createWidget ) {
 			return new $[ namespace ][ name ]( options, element );