Dialog: Append the dialog to the body early to make sure styles from the classes get applied.

ui/jquery.ui.dialog.js

@@ -108,7 +108,8 @@ $.widget("ui.dialog", {
 				})
 				.mousedown(function( event ) {
 					self.moveToTop( false, event );
-				}),
+				})
+				.appendTo( "body" ),
 
 			uiDialogContent = self.element
 				.show()
@@ -155,8 +156,6 @@ $.widget("ui.dialog", {
 		self._createButtons( options.buttons );
 		self._isOpen = false;
 
-		uiDialog.appendTo( document.body );
-
 		if ( $.fn.bgiframe ) {
 			uiDialog.bgiframe();
 		}