--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -6458,59 +6458,62 @@ var MailIntegration = {
          .getService(Ci.nsIExternalProtocolService);
     if (extProtocolSvc)
       extProtocolSvc.loadUrl(aURL);
   }
 };
 
 function BrowserOpenAddonsMgr(aView) {
   return new Promise(resolve => {
-    if (aView) {
-      let emWindow;
-      let browserWindow;
-
-      var receivePong = function(aSubject, aTopic, aData) {
-        let browserWin = aSubject.QueryInterface(Ci.nsIInterfaceRequestor)
-                                 .getInterface(Ci.nsIWebNavigation)
-                                 .QueryInterface(Ci.nsIDocShellTreeItem)
-                                 .rootTreeItem
-                                 .QueryInterface(Ci.nsIInterfaceRequestor)
-                                 .getInterface(Ci.nsIDOMWindow);
-        if (!emWindow || browserWin == window /* favor the current window */) {
-          emWindow = aSubject;
-          browserWindow = browserWin;
-        }
+    let emWindow;
+    let browserWindow;
+
+    var receivePong = function(aSubject, aTopic, aData) {
+      let browserWin = aSubject.QueryInterface(Ci.nsIInterfaceRequestor)
+                               .getInterface(Ci.nsIWebNavigation)
+                               .QueryInterface(Ci.nsIDocShellTreeItem)
+                               .rootTreeItem
+                               .QueryInterface(Ci.nsIInterfaceRequestor)
+                               .getInterface(Ci.nsIDOMWindow);
+      if (!emWindow || browserWin == window /* favor the current window */) {
+        emWindow = aSubject;
+        browserWindow = browserWin;
       }
-      Services.obs.addObserver(receivePong, "EM-pong", false);
-      Services.obs.notifyObservers(null, "EM-ping", "");
-      Services.obs.removeObserver(receivePong, "EM-pong");
-
-      if (emWindow) {
+    }
+    Services.obs.addObserver(receivePong, "EM-pong", false);
+    Services.obs.notifyObservers(null, "EM-ping", "");
+    Services.obs.removeObserver(receivePong, "EM-pong");
+
+    if (emWindow) {
+      if (aView) {
         emWindow.loadView(aView);
-        browserWindow.gBrowser.selectedTab =
-          browserWindow.gBrowser._getTabForContentWindow(emWindow);
-        emWindow.focus();
-        resolve(emWindow);
-        return;
       }
-    }
-
-    switchToTabHavingURI("about:addons", true);
-
-    if (aView) {
-      // This must be a new load, else the ping/pong would have
-      // found the window above.
-      Services.obs.addObserver(function observer(aSubject, aTopic, aData) {
-        Services.obs.removeObserver(observer, aTopic);
+      browserWindow.gBrowser.selectedTab =
+        browserWindow.gBrowser._getTabForContentWindow(emWindow);
+      emWindow.focus();
+      resolve(emWindow);
+      return;
+    }
+
+    // This must be a new load, else the ping/pong would have
+    // found the window above.
+    let whereToOpen = (window.gBrowser && isTabEmpty(gBrowser.selectedTab)) ?
+                      "current" :
+                      "tab";
+    openUILinkIn("about:addons", whereToOpen);
+
+    Services.obs.addObserver(function observer(aSubject, aTopic, aData) {
+      Services.obs.removeObserver(observer, aTopic);
+      if (aView) {
         aSubject.loadView(aView);
-        resolve(aSubject);
-      }, "EM-loaded", false);
-    } else {
-      resolve();
-    }
+      }
+      aSubject.QueryInterface(Ci.nsIDOMWindow);
+      aSubject.focus();
+      resolve(aSubject);
+    }, "EM-loaded", false);
   });
 }
 
 function AddKeywordForSearchField() {
   let mm = gBrowser.selectedBrowser.messageManager;
 
   let onMessage = (message) => {
     mm.removeMessageListener("ContextMenu:SearchFieldBookmarkData:Result", onMessage);