#13685:

+ moved plugin zIndex from previous version

lib/web/jquery/jquery-ui.js

@@ -19,6 +19,39 @@ $.ui = $.ui || {};
 
 var version = $.ui.version = "1.12.1";
 
+// plugins
+    $.fn.extend({
+        zIndex: function( zIndex ) {
+            if ( zIndex !== undefined ) {
+                return this.css( "zIndex", zIndex );
+            }
+
+            if ( this.length ) {
+                var elem = $( this[ 0 ] ), position, value;
+                while ( elem.length && elem[ 0 ] !== document ) {
+                    // Ignore z-index if position is set to a value where z-index is ignored by the browser
+                    // This makes behavior of this function consistent across browsers
+                    // WebKit always returns auto if the element is positioned
+                    position = elem.css( "position" );
+                    if ( position === "absolute" || position === "relative" || position === "fixed" ) {
+                        // IE returns 0 when zIndex is not specified
+                        // other browsers return a string
+                        // we ignore the case of nested elements with an explicit value of 0
+                        // <div style="z-index: -10;"><div style="z-index: 0;"></div></div>
+                        value = parseInt( elem.css( "zIndex" ), 10 );
+                        if ( !isNaN( value ) && value !== 0 ) {
+                            return value;
+                        }
+                    }
+                    elem = elem.parent();
+                }
+            }
+
+            return 0;
+        }
+
+    });
+
 /*!
  * jQuery UI Widget 1.12.1
  * http://jqueryui.com