diff -r 000000000000 -r 6474c204b198 browser/devtools/debugger/test/browser_dbg_variables-view-popup-10.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/debugger/test/browser_dbg_variables-view-popup-10.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,61 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * Makes sure the source editor's scroll location doesn't change when
+ * a variable inspection popup is opened and a watch expression is
+ * also evaluated at the same time.
+ */
+
+const TAB_URL = EXAMPLE_URL + "doc_frame-parameters.html";
+
+function test() {
+  Task.spawn(function() {
+    let [tab, debuggee, panel] = yield initDebugger(TAB_URL);
+    let win = panel.panelWin;
+    let events = win.EVENTS;
+    let editor = win.DebuggerView.editor;
+    let editorContainer = win.document.getElementById("editor");
+    let bubble = win.DebuggerView.VariableBubble;
+    let expressions = win.DebuggerView.WatchExpressions;
+    let tooltip = bubble._tooltip.panel;
+
+    // Allow this generator function to yield first.
+    executeSoon(() => debuggee.start());
+    yield waitForSourceAndCaretAndScopes(panel, ".html", 24);
+
+    let expressionsEvaluated = waitForDebuggerEvents(panel, events.FETCHED_WATCH_EXPRESSIONS);
+    expressions.addExpression("this");
+    editor.focus();
+    yield expressionsEvaluated;
+
+    // Scroll to the top of the editor and inspect variables.
+    let breakpointScrollPosition = editor.getScrollInfo().top;
+    editor.setFirstVisibleLine(0);
+    let topmostScrollPosition = editor.getScrollInfo().top;
+
+    ok(topmostScrollPosition < breakpointScrollPosition,
+      "The editor is now scrolled to the top (0).");
+    is(editor.getFirstVisibleLine(), 0,
+      "The editor is now scrolled to the top (1).");
+
+    let failPopup = () => ok(false, "The popup has got unexpectedly hidden.");
+    let failScroll = () => ok(false, "The editor has got unexpectedly scrolled.");
+    tooltip.addEventListener("popuphiding", failPopup);
+    editorContainer.addEventListener("scroll", failScroll);
+    editor.on("scroll", () => {
+      if (editor.getScrollInfo().top > topmostScrollPosition) {
+        ok(false, "The editor scrolled back to the breakpoint location.");
+      }
+    });
+
+    let expressionsEvaluated = waitForDebuggerEvents(panel, events.FETCHED_WATCH_EXPRESSIONS);
+    yield openVarPopup(panel, { line: 14, ch: 15 });
+    yield expressionsEvaluated;
+
+    tooltip.removeEventListener("popuphiding", failPopup);
+    editorContainer.removeEventListener("scroll", failScroll);
+
+    yield resumeDebuggerThenCloseAndFinish(panel);
+  });
+}