--- a/browser/base/content/tabview/ui.js
+++ b/browser/base/content/tabview/ui.js
@@ -195,21 +195,16 @@ let UI = {
           } else {
             self._lastClick = Date.now();
             self._lastClickPositions = new Point(e.clientX, e.clientY);
             self._createGroupItemOnDrag(e);
           }
         }
       });
 
-      iQ(window).bind("beforeunload", function() {
-        Array.forEach(gBrowser.tabs, function(tab) {
-          gBrowser.showTab(tab);
-        });
-      });
       iQ(window).bind("unload", function() {
         self.uninit();
       });
 
       gWindow.addEventListener("tabviewhide", function() {
         self.exit();
       }, false);