diff --git a/mozilla/widget/public/nsIWidget.h b/mozilla/widget/public/nsIWidget.h
index ebfb3d8c3a4..1f665edc6a7 100644
--- a/mozilla/widget/public/nsIWidget.h
+++ b/mozilla/widget/public/nsIWidget.h
@@ -297,8 +297,6 @@ class nsIWidget : public nsISupports {
     /**
      * Make the window modal 
      *
-     * 
-     *
      */
     NS_IMETHOD SetModal(void) = 0;
 
@@ -345,6 +343,16 @@ class nsIWidget : public nsISupports {
                       PRInt32 aHeight,
                       PRBool   aRepaint) = 0;
 
+    /**
+     * Set's the widget's z-index.
+     */
+    NS_IMETHOD SetZIndex(PRInt32 aZIndex) = 0;
+
+    /**
+     * Get's the widget's z-index. 
+     */
+    NS_IMETHOD GetZIndex(PRInt32* aZIndex) = 0;
+
     /**
      * Enable or disable this Widget
      *
diff --git a/mozilla/widget/src/xpwidgets/nsBaseWidget.cpp b/mozilla/widget/src/xpwidgets/nsBaseWidget.cpp
index e76ad888083..92b907dbc52 100644
--- a/mozilla/widget/src/xpwidgets/nsBaseWidget.cpp
+++ b/mozilla/widget/src/xpwidgets/nsBaseWidget.cpp
@@ -61,6 +61,7 @@ nsBaseWidget::nsBaseWidget()
 ,	mOnDestroyCalled(PR_FALSE)
 ,	mBounds(0,0,0,0)
 ,	mVScrollbar(nsnull)
+,   mZIndex(0)
 {
     NS_NewISupportsArray(getter_AddRefs(mChildren));
     
@@ -245,7 +246,56 @@ void nsBaseWidget::RemoveChild(nsIWidget* aChild)
 {
   mChildren->RemoveElement(aChild);
 }
-    
+
+
+//-------------------------------------------------------------------------
+//
+// Sets widget's position within its parent's child list.
+//
+//-------------------------------------------------------------------------
+NS_IMETHODIMP nsBaseWidget::SetZIndex(PRInt32 aZIndex)
+{
+	mZIndex = aZIndex;
+
+	// reorder this child in its parent's list.
+	nsBaseWidget* parent = NS_STATIC_CAST(nsBaseWidget*, GetParent());
+	if (nsnull != parent) {
+		parent->mChildren->RemoveElement(this);
+		PRUint32 childCount, index;
+		if (NS_SUCCEEDED(parent->mChildren->Count(&childCount))) {
+			for (index = 0; index < childCount; index++) {
+				nsCOMPtr<nsIWidget> childWidget;
+				if (NS_SUCCEEDED(parent->mChildren->QueryElementAt(index, NS_GET_IID(nsIWidget), (void**)getter_AddRefs(childWidget)))) {
+					PRInt32 childZIndex;
+					if (NS_SUCCEEDED(childWidget->GetZIndex(&childZIndex))) {
+						if (aZIndex < childZIndex) {
+							parent->mChildren->InsertElementAt(this, index);
+							break;
+						}
+					}
+				}
+			}
+			// were we added to the list?
+			if (index == childCount) {
+				parent->mChildren->AppendElement(this);
+			}
+		}
+		NS_RELEASE(parent);
+	}
+	return NS_OK;
+}
+
+//-------------------------------------------------------------------------
+//
+// Gets widget's position within its parent's child list.
+//
+//-------------------------------------------------------------------------
+NS_IMETHODIMP nsBaseWidget::GetZIndex(PRInt32* aZIndex)
+{
+	*aZIndex = mZIndex;
+	return NS_OK;
+}
+
 //-------------------------------------------------------------------------
 //
 // Get the foreground color
diff --git a/mozilla/widget/src/xpwidgets/nsBaseWidget.h b/mozilla/widget/src/xpwidgets/nsBaseWidget.h
index 7b0f5c827bf..318df2ac482 100644
--- a/mozilla/widget/src/xpwidgets/nsBaseWidget.h
+++ b/mozilla/widget/src/xpwidgets/nsBaseWidget.h
@@ -61,6 +61,8 @@ public:
     virtual void            AddChild(nsIWidget* aChild);
     virtual void            RemoveChild(nsIWidget* aChild);
 
+    NS_IMETHOD              SetZIndex(PRInt32 aZIndex);
+    NS_IMETHOD              GetZIndex(PRInt32* aZIndex);
 
     virtual nscolor         GetForegroundColor(void);
     NS_IMETHOD              SetForegroundColor(const nscolor &aColor);
@@ -129,13 +131,12 @@ protected:
     PRBool            mIsAltDown;
     PRBool            mIsDestroying;
     PRBool            mOnDestroyCalled;
-    //PRInt32           mWidth;
-    //PRInt32           mHeight;
     nsRect            mBounds;
     nsIWidget        *mVScrollbar;
+    PRInt32           mZIndex;
 
     // keep the list of children
-    nsCOMPtr<nsISupportsArray> mChildren;    
+    nsCOMPtr<nsISupportsArray> mChildren;
     
     class Enumerator : public nsIBidirectionalEnumerator {
     public: