From a6fdb77472d0999a95c9e6818e229dab409db51c Mon Sep 17 00:00:00 2001
From: Jason Grout <jgrout6@bloomberg.net>
Date: Fri, 26 Jul 2019 12:11:46 -0700
Subject: [PATCH] Only create tab keys if we have a tab bar renderer.

---
 packages/widgets/src/docklayout.ts | 11 +++++++----
 packages/widgets/src/tabbar.ts     | 13 -------------
 packages/widgets/src/tabpanel.ts   |  8 ++++++--
 3 files changed, 13 insertions(+), 19 deletions(-)

diff --git a/packages/widgets/src/docklayout.ts b/packages/widgets/src/docklayout.ts
index 78deb386f..fca1d254c 100644
--- a/packages/widgets/src/docklayout.ts
+++ b/packages/widgets/src/docklayout.ts
@@ -1994,14 +1994,17 @@ namespace Private {
   }
 
   export
-  async function addAria(widget: Widget, tabBar: TabBar<Widget>) {
-    let tabId = tabBar.renderer.createTabKey({title: widget.title, current: false, zIndex: 0});
+  function addAria(widget: Widget, tabBar: TabBar<Widget>) {
     widget.node.setAttribute('role', 'tabpanel');
-    widget.node.setAttribute('aria-labelledby', tabId);
+    let renderer = tabBar.renderer;
+    if (renderer instanceof TabBar.Renderer) {
+      let tabId = renderer.createTabKey({ title: widget.title, current: false, zIndex: 0 });
+      widget.node.setAttribute('aria-labelledby', tabId);  
+    }
   }
 
   export
-  async function removeAria(widget: Widget) {
+  function removeAria(widget: Widget) {
     widget.node.removeAttribute('role');
     widget.node.removeAttribute('aria-labelledby');
   }
diff --git a/packages/widgets/src/tabbar.ts b/packages/widgets/src/tabbar.ts
index 4255459a1..7cbe87c95 100644
--- a/packages/widgets/src/tabbar.ts
+++ b/packages/widgets/src/tabbar.ts
@@ -1434,19 +1434,6 @@ namespace TabBar {
      * @returns A virtual element representing the tab.
      */
     renderTab(data: IRenderData<T>): VirtualElement;
-
-    /**
-     * Create a stable unique id for a tab based on the title.
-     *
-     * @param data - The data to use for the tab.
-     *
-     * @returns The unique id for a tab.
-     *
-     * #### Notes
-     * This method returns a stable unique id for a tab, depending only on the
-     * title. The tab DOM `id` is set to this value.
-     */
-    createTabKey(data: IRenderData<T>): string;
   }
 
   /**
diff --git a/packages/widgets/src/tabpanel.ts b/packages/widgets/src/tabpanel.ts
index 375de3699..7b324ca1e 100644
--- a/packages/widgets/src/tabpanel.ts
+++ b/packages/widgets/src/tabpanel.ts
@@ -273,9 +273,13 @@ class TabPanel extends Widget {
     this.stackedPanel.insertWidget(index, widget);
     this.tabBar.insertTab(index, widget.title);
 
-    let tabId = this.tabBar.renderer.createTabKey({title: widget.title, current: false, zIndex: 0});
     widget.node.setAttribute('role', 'tabpanel');
-    widget.node.setAttribute('aria-labelledby', tabId);
+
+    let renderer = this.tabBar.renderer
+    if (renderer instanceof TabBar.Renderer) {
+      let tabId = renderer.createTabKey({title: widget.title, current: false, zIndex: 0});
+      widget.node.setAttribute('aria-labelledby', tabId);
+    }
   }
 
   /**