diff --git a/www/manager6/Toolkit.js b/www/manager6/Toolkit.js
index 263dea16..ff59a55a 100644
--- a/www/manager6/Toolkit.js
+++ b/www/manager6/Toolkit.js
@@ -112,6 +112,39 @@ Ext.override(Ext.form.field.ComboBox, {
     }
 });
 
+// ExtJs 5-6 has an issue with caching
+// see https://www.sencha.com/forum/showthread.php?308989
+Ext.define('PVE.UnderlayPool', {
+    override: 'Ext.dom.UnderlayPool',
+
+    checkOut: function () {
+        var cache = this.cache,
+            len = cache.length,
+            el;
+
+        // do cleanup because some of the objects might have been destroyed
+	while (len--) {
+            if (cache[len].destroyed) {
+                cache.splice(len, 1);
+            }
+        }
+        // end do cleanup
+
+	el = cache.shift();
+
+        if (!el) {
+            el = Ext.Element.create(this.elementConfig);
+            el.setVisibilityMode(2);
+            //<debug>
+            // tell the spec runner to ignore this element when checking if the dom is clean
+	    el.dom.setAttribute('data-sticky', true);
+            //</debug>
+	}
+
+        return el;
+    }
+});
+
 Ext.define('Ext.ux.IFrame', {
     extend: 'Ext.Component',