--- a/layout/xul/test/Makefile.in
+++ b/layout/xul/test/Makefile.in
@@ -21,13 +21,14 @@ MOCHITEST_CHROME_FILES = \
 		test_bug159346.xul \
 		test_bug372685.xul \
 		test_bug398982-1.xul \
 		test_bug398982-2.xul \
 		test_bug703150.xul \
 		$(NULL)
 
 MOCHITEST_BROWSER_FILES = \
+		browser_bug685470.js \
 		browser_bug703210.js \
 		browser_bug706743.js \
 		$(NULL)
 
 include $(topsrcdir)/config/rules.mk

new file mode 100644
--- /dev/null
+++ b/layout/xul/test/browser_bug685470.js
@@ -0,0 +1,56 @@
+function test() {
+  waitForExplicitFinish();
+
+  gBrowser.selectedTab = gBrowser.addTab();
+
+  SpecialPowers.setIntPref("ui.tooltipDelay", 0);
+
+  var popup = false;
+  var doc;
+  var win;
+  var p1;
+
+  let onPopupShown = function(aEvent) {
+    popup = true;
+  }
+
+  // test that a mouse click prior to the tooltip appearing blocks it and
+  // mouse movement without leaving the target doesn't show it
+  let runTest = function() {
+    var rc = p1.getBoundingClientRect();
+
+    EventUtils.synthesizeMouseAtCenter(p1, { type: "mousemove" }, win);
+    EventUtils.sendMouseEvent({type:'mousedown'}, p1, win);
+    EventUtils.sendMouseEvent({type:'mouseup'}, p1, win);
+    EventUtils.synthesizeMouse(p1, rc.left, rc.top, { type: "mousemove" }, win);
+
+    setTimeout(function() {
+      is(popup, false, "shouldn't get tooltip after click and mouse move " +
+                       "within target");
+
+      document.removeEventListener("popupshown", onPopupShown, true);
+      SpecialPowers.clearUserPref("ui.tooltipDelay");
+
+      gBrowser.removeCurrentTab();
+      finish();
+    }, 200);
+  }
+
+  let onLoad = function (aEvent) {
+    doc = gBrowser.contentDocument;
+    win = gBrowser.contentWindow;
+    p1 = doc.getElementById("p1");
+
+    document.addEventListener("popupshown", onPopupShown, true);
+
+    runTest();
+  }
+
+  gBrowser.selectedBrowser.addEventListener("load", function loadListener() {
+    gBrowser.selectedBrowser.removeEventListener("load", loadListener, true);
+    setTimeout(onLoad, 0);
+  }, true);
+
+  content.location = "data:text/html," +
+    "<p id=\"p1\" title=\"tooltip is here\">This paragraph has a tooltip.</p>";
+}