Dialog: Don't return true when we don't want to cancel events. Fixes …

…#3523 - Dialog: onclick return value ignored.

ui/jquery.ui.dialog.js

@@ -693,7 +693,10 @@ $.extend($.ui.dialog.overlay, {
				if ($.ui.dialog.overlay.instances.length) {
					$(document).bind($.ui.dialog.overlay.events, function(event) {
						// stop events if the z-index of the target is < the z-index of the overlay
						return ($(event.target).zIndex() >= $.ui.dialog.overlay.maxZ);
						// we cannot return true when we don't want to cancel the event (#3523)
						if ($(event.target).zIndex() < $.ui.dialog.overlay.maxZ) {
							return false;
						}
					});
				}
			}, 1);