diff --git a/mozilla/docshell/base/nsDocShell.cpp b/mozilla/docshell/base/nsDocShell.cpp
index b1a74ea0f26..773faa20227 100644
--- a/mozilla/docshell/base/nsDocShell.cpp
+++ b/mozilla/docshell/base/nsDocShell.cpp
@@ -3757,8 +3757,16 @@ nsDocShell::GetVisibility(PRBool * aVisibility)
         treeItem->GetParent(getter_AddRefs(parentItem));
     }
 
-    *aVisibility = PR_TRUE;
-    return NS_OK;
+    nsCOMPtr<nsIBaseWindow>
+        treeOwnerAsWin(do_QueryInterface(mTreeOwner));
+    if (!treeOwnerAsWin) {
+        *aVisibility = PR_TRUE;
+        return NS_OK;
+    }
+
+    // Check with the tree owner as well to give embedders a chance to
+    // expose visibility as well.
+    return treeOwnerAsWin->GetVisibility(aVisibility);
 }
 
 NS_IMETHODIMP
diff --git a/mozilla/xpfe/appshell/src/nsXULWindow.cpp b/mozilla/xpfe/appshell/src/nsXULWindow.cpp
index e66a3c9dd35..e0f1777591f 100644
--- a/mozilla/xpfe/appshell/src/nsXULWindow.cpp
+++ b/mozilla/xpfe/appshell/src/nsXULWindow.cpp
@@ -739,9 +739,12 @@ NS_IMETHODIMP nsXULWindow::GetVisibility(PRBool* aVisibility)
 {
   NS_ENSURE_ARG_POINTER(aVisibility);
 
-   //XXX First Check In
-   NS_ASSERTION(PR_FALSE, "Not Yet Implemented");
-   return NS_OK;
+  // Always claim to be visible for now. See bug
+  // https://bugzilla.mozilla.org/show_bug.cgi?id=306245.
+
+  *aVisibility = PR_TRUE;
+
+  return NS_OK;
 }
 
 NS_IMETHODIMP nsXULWindow::SetVisibility(PRBool aVisibility)