diff -r 000000000000 -r 6474c204b198 browser/components/tabview/test/browser_tabview_bug629189.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/components/tabview/test/browser_tabview_bug629189.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,14 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+function test() {
+  let {Rect} = Components.utils.import("resource:///modules/tabview/utils.jsm", {});
+  
+  let referenceRect = new Rect(50,50,150,150);
+  let rect = new Rect(100,100,100,100);
+  
+  ok(referenceRect.contains(referenceRect), "A rect contains itself");
+  ok(referenceRect.contains(rect), "[50,50,150,150] contains [100,100,100,100]");
+  rect.inset(-1,-1);
+  ok(!referenceRect.contains(rect), "Now it grew and [50,50,150,150] doesn't contain [99,99,102,102]");
+}