Dialog: Fixed #4086: Allow changing the dialogClass option after init.

ui/ui.dialog.js

@@ -25,7 +25,13 @@ var setDataSwitch = {
 		resizeStart: "start.resizable",
 		resize: "drag.resizable",
 		resizeStop: "stop.resizable"
-};
+	},
+	
+	uiDialogClasses =
+		'ui-dialog ' +
+		'ui-widget ' +
+		'ui-widget-content ' +
+		'ui-corner-all ';
 
 $.widget("ui.dialog", {
 
@@ -41,13 +47,7 @@ $.widget("ui.dialog", {
 			uiDialog = (this.uiDialog = $('<div/>'))
 				.appendTo(document.body)
 				.hide()
-				.addClass(
-					'ui-dialog ' +
-					'ui-widget ' +
-					'ui-widget-content ' +
-					'ui-corner-all ' +
-					options.dialogClass
-				)
+				.addClass(uiDialogClasses + options.dialogClass)
 				.css({
 					position: 'absolute',
 					overflow: 'hidden',
@@ -402,6 +402,11 @@ $.widget("ui.dialog", {
 			case "closeText":
 				this.uiDialogTitlebarCloseText.text(value);
 				break;
+			case "dialogClass":
+				this.uiDialog
+					.removeClass(this.options.dialogClass)
+					.addClass(uiDialogClasses + value);
+				break;
 			case "draggable":
 				(value
 					? this._makeDraggable()