diff --git a/layout/xul/base/public/nsXULPopupManager.h b/layout/xul/base/public/nsXULPopupManager.h
index ef55868bb4f..6dc42957cec 100644
--- a/layout/xul/base/public/nsXULPopupManager.h
+++ b/layout/xul/base/public/nsXULPopupManager.h
@@ -46,6 +46,7 @@
 #include "nsIRollupListener.h"
 #include "nsIMenuRollup.h"
 #include "nsIDOMKeyListener.h"
+#include "nsPoint.h"
 #include "nsCOMPtr.h"
 #include "nsTArray.h"
 #include "nsITimer.h"
@@ -359,8 +360,9 @@ public:
   // This is used by the implementation of nsIDOMXULDocument::GetPopupRangeParent
   // and nsIDOMXULDocument::GetPopupRangeOffset.
   void GetMouseLocation(nsIDOMNode** aNode, PRInt32* aOffset);
-  // set the mouse event that was used to activate the next popup to be opened.
-  void SetMouseLocation(nsIDOMEvent* aEvent);
+  // set the mouse event that was used to activate the next popup, specified by
+  // aPopup, to be opened.
+  void SetMouseLocation(nsIDOMEvent* aEvent, nsIContent* aPopup);
 
   /**
    * Open a <menu> given its content node. If aSelectFirstItem is
@@ -626,6 +628,7 @@ protected:
   // range parent and offset set in SetMouseLocation
   nsCOMPtr<nsIDOMNode> mRangeParent;
   PRInt32 mRangeOffset;
+  nsPoint mCachedMousePoint;
 
   // set to the currently active menu bar, if any
   nsMenuBarFrame* mActiveMenuBar;
diff --git a/layout/xul/base/src/nsXULPopupManager.cpp b/layout/xul/base/src/nsXULPopupManager.cpp
index 69885c734ad..96b97ddca22 100644
--- a/layout/xul/base/src/nsXULPopupManager.cpp
+++ b/layout/xul/base/src/nsXULPopupManager.cpp
@@ -45,6 +45,7 @@
 #include "nsIDOMDocument.h"
 #include "nsIDOMNSEvent.h"
 #include "nsIDOMNSUIEvent.h"
+#include "nsIPrivateDOMEvent.h"
 #include "nsEventDispatcher.h"
 #include "nsCSSFrameConstructor.h"
 #include "nsLayoutUtils.h"
@@ -236,13 +237,40 @@ nsXULPopupManager::GetMouseLocation(nsIDOMNode** aNode, PRInt32* aOffset)
 }
 
 void
-nsXULPopupManager::SetMouseLocation(nsIDOMEvent* aEvent)
+nsXULPopupManager::SetMouseLocation(nsIDOMEvent* aEvent, nsIContent* aPopup)
 {
+  mCachedMousePoint = nsPoint(0, 0);
+
   nsCOMPtr<nsIDOMNSUIEvent> uiEvent = do_QueryInterface(aEvent);
-  NS_ASSERTION(uiEvent, "Expected an nsIDOMNSUIEvent");
+  NS_ASSERTION(!aEvent || uiEvent, "Expected an nsIDOMNSUIEvent");
   if (uiEvent) {
     uiEvent->GetRangeParent(getter_AddRefs(mRangeParent));
     uiEvent->GetRangeOffset(&mRangeOffset);
+
+    // get the event coordinates relative to the root frame of the document
+    // containing the popup.
+    nsCOMPtr<nsIPrivateDOMEvent> privateEvent(do_QueryInterface(aEvent));
+    if (privateEvent) {
+      NS_ASSERTION(aPopup, "Expected a popup node");
+      nsEvent* event;
+      nsresult rv = privateEvent->GetInternalNSEvent(&event);
+      if (NS_SUCCEEDED(rv) && event) {
+        nsIDocument* doc = aPopup->GetCurrentDoc();
+        if (doc) {
+          nsIPresShell* presShell = doc->GetPrimaryShell();
+          if (presShell) {
+            nsPresContext* presContext = presShell->GetPresContext();
+            nsIFrame* rootFrame = presShell->GetRootFrame();
+            if (rootFrame && presContext) {
+              nsPoint pnt =
+                nsLayoutUtils::GetEventCoordinatesRelativeTo(event, rootFrame);
+              mCachedMousePoint = nsPoint(presContext->AppUnitsToDevPixels(pnt.x),
+                                          presContext->AppUnitsToDevPixels(pnt.y));
+            }
+          }
+        }
+      }
+    }
   }
   else {
     mRangeParent = nsnull;
@@ -293,6 +321,7 @@ nsXULPopupManager::ShowMenu(nsIContent *aMenu,
   popupFrame->InitializePopup(aMenu, position, 0, 0, PR_TRUE);
 
   if (aAsynchronous) {
+    SetMouseLocation(nsnull, nsnull);
     nsCOMPtr<nsIRunnable> event =
       new nsXULPopupShowingEvent(popupFrame->GetContent(), aMenu,
                                  parentIsContextMenu, aSelectFirstItem);
@@ -539,7 +568,7 @@ nsXULPopupManager::HidePopupCallback(nsIContent* aPopup,
 
   // send the popuphidden event synchronously. This event has no default behaviour.
   nsEventStatus status = nsEventStatus_eIgnore;
-  nsEvent event(PR_TRUE, NS_XUL_POPUP_HIDDEN);
+  nsMouseEvent event(PR_TRUE, NS_XUL_POPUP_HIDDEN, nsnull, nsMouseEvent::eReal);
   nsEventDispatcher::Dispatch(aPopup, aPopupFrame->PresContext(),
                               &event, nsnull, &status);
 
@@ -678,8 +707,13 @@ nsXULPopupManager::FirePopupShowingEvent(nsIContent* aPopup,
   //   is where those details would be retrieved. This removes the need for
   //   all the globals people keep adding to nsIDOMXULDocument.
   nsEventStatus status = nsEventStatus_eIgnore;
-  nsEvent event(PR_TRUE, NS_XUL_POPUP_SHOWING);
+  nsMouseEvent event(PR_TRUE, NS_XUL_POPUP_SHOWING, nsnull, nsMouseEvent::eReal);
+  nsPoint pnt;
+  event.widget = presShell->GetRootFrame()->
+                            GetClosestView()->GetNearestWidget(&pnt);
+  event.refPoint = mCachedMousePoint;
   nsEventDispatcher::Dispatch(aPopup, aPresContext, &event, nsnull, &status);
+  mCachedMousePoint = nsPoint(0, 0);
 
   // it is common to append content to the menu during the popupshowing event.
   // Flush the notifications so that the frames are up to date before showing
@@ -712,7 +746,7 @@ nsXULPopupManager::FirePopupHidingEvent(nsIContent* aPopup,
   nsCOMPtr<nsIPresShell> presShell = aPresContext->PresShell();
 
   nsEventStatus status = nsEventStatus_eIgnore;
-  nsEvent event(PR_TRUE, NS_XUL_POPUP_HIDING);
+  nsMouseEvent event(PR_TRUE, NS_XUL_POPUP_HIDING, nsnull, nsMouseEvent::eReal);
   nsEventDispatcher::Dispatch(aPopup, aPresContext, &event, nsnull, &status);
 
   // get frame again in case it went away
diff --git a/toolkit/content/tests/widgets/Makefile.in b/toolkit/content/tests/widgets/Makefile.in
index 8a7d5fb8c80..309052fc0a3 100644
--- a/toolkit/content/tests/widgets/Makefile.in
+++ b/toolkit/content/tests/widgets/Makefile.in
@@ -48,6 +48,7 @@ _TEST_FILES = 	test_bug360220.xul \
 		test_bug359754.xul \
 		test_bug365773.xul \
 		test_colorpicker_popup.xul \
+		test_popup_coords.xul \
 		$(NULL)
 
 libs:: $(_TEST_FILES)
diff --git a/toolkit/content/tests/widgets/test_popup_coords.xul b/toolkit/content/tests/widgets/test_popup_coords.xul
new file mode 100644
index 00000000000..281149d1a06
--- /dev/null
+++ b/toolkit/content/tests/widgets/test_popup_coords.xul
@@ -0,0 +1,88 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<?xml-stylesheet href="/tests/SimpleTest/test.css" type="text/css"?>
+
+<window title="Popup Coordinate Tests"
+  onload="setTimeout(openThePopup, 0, 'outer');"
+  xmlns:html="http://www.w3.org/1999/xhtml"
+  xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+
+  <title>Popup Tests</title>
+  <script type="application/javascript" src="/MochiKit/packed.js"></script>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>      
+  <script type="application/javascript" src="/tests/SimpleTest/EventUtils.js"></script>      
+
+<deck style="margin-top: 5px; padding-top: 5px;">
+  <label id="outer" popup="outerpopup" value="Popup"/>
+</deck>
+
+<panel id="outerpopup"
+           onpopupshowing="popupShowingEventOccured(event);"
+           onpopupshown="eventOccured(event); openThePopup('inner')"
+           onpopuphiding="eventOccured(event);"
+           onpopuphidden="eventOccured(event); SimpleTest.finish();">
+  <button id="item1" label="First"/>
+  <label id="inner" value="Second" popup="innerpopup"/>
+  <button id="item2" label="Third"/>
+</panel>
+
+<menupopup id="innerpopup"
+           onpopupshowing="popupShowingEventOccured(event);"
+           onpopupshown="eventOccured(event); event.target.hidePopup();"
+           onpopuphiding="eventOccured(event);"
+           onpopuphidden="eventOccured(event); document.getElementById('outerpopup').hidePopup();">
+  <menuitem id="inner1" label="Inner First"/>
+  <menuitem id="inner2" label="Inner Second"/>
+</menupopup>
+
+<script>
+SimpleTest.waitForExplicitFinish();
+
+function openThePopup(id)
+{
+  if (id == "inner")
+    document.getElementById("item1").focus();
+
+  var trigger = document.getElementById(id);
+  synthesizeMouse(trigger, 4, 5, { });
+}
+
+function eventOccured(event)
+{
+  var testname = event.type + " on " + event.target.id + " ";
+  ok(event instanceof MouseEvent, testname + "is a mouse event");
+  is(event.clientX, 0, testname + "clientX");
+  is(event.clientY, 0, testname + "clientY");
+  is(event.rangeParent, null, testname + "rangeParent");
+  is(event.rangeOffset, 0, testname + "rangeOffset");
+}
+
+function popupShowingEventOccured(event)
+{
+  // the popupshowing event should have the event coordinates and
+  // range position filled in.
+  var testname = "popupshowing on " + event.target.id + " ";
+  ok(event instanceof MouseEvent, testname + "is a mouse event");
+
+  var trigger = document.getElementById(event.target.id == "outerpopup" ? "outer" : "inner");
+  var rect = trigger.getBoundingClientRect();
+  is(event.clientX, Math.round(rect.left) + 4, testname + "clientX");
+  is(event.clientY, Math.round(rect.top) + 5, testname + "clientY");
+  // rangeOffset should be just after the trigger element. As rangeOffset
+  // considers the zeroth position to be before the first element, the value
+  // should be one higher than its index within its parent.
+  is(event.rangeParent, trigger.parentNode, testname + "rangeParent");
+  is(event.rangeOffset, Array.indexOf(trigger.parentNode.childNodes, trigger) + 1, testname + "rangeOffset");
+}
+</script>
+
+<body xmlns="http://www.w3.org/1999/xhtml">
+<p id="display">
+</p>
+<div id="content" style="display: none">
+</div>
+<pre id="test">
+</pre>
+</body>
+
+</window>