diff --git a/mozilla/widget/public/nsIWidget.h b/mozilla/widget/public/nsIWidget.h
index eab1b1129cd..eaa511b144b 100644
--- a/mozilla/widget/public/nsIWidget.h
+++ b/mozilla/widget/public/nsIWidget.h
@@ -653,6 +653,13 @@ class nsIWidget : public nsISupports {
     NS_IMETHOD EnableFileDrop(PRBool aEnable) = 0;
    
     virtual void  ConvertToDeviceCoordinates(nscoord	&aX,nscoord	&aY) = 0;
+
+    /**
+     * Enables/Disables system mouse capture.
+     * @param aCapture PR_TRUE enables mouse capture, PR_FALSE disables mouse capture 
+     *
+     */
+    NS_IMETHOD CaptureMouse(PRBool aCapture) = 0;
 };
 
 #endif // nsIWidget_h__
diff --git a/mozilla/widget/src/windows/nsWindow.cpp b/mozilla/widget/src/windows/nsWindow.cpp
index cc1f8b8034a..6e5c74eacca 100644
--- a/mozilla/widget/src/windows/nsWindow.cpp
+++ b/mozilla/widget/src/windows/nsWindow.cpp
@@ -155,6 +155,17 @@ nsWindow::~nsWindow()
 }
 
 
+NS_METHOD nsWindow::CaptureMouse(PRBool aCapture)
+{
+  if (PR_TRUE == aCapture) { 
+    SetCapture(mWnd);
+  } else {
+    ReleaseCapture();
+  }
+  return NS_OK;
+}
+
+
 //-------------------------------------------------------------------------
 //
 // Default for height modification is to do nothing
@@ -2017,7 +2028,7 @@ BOOL nsWindow::OnKeyDown( UINT aVirtualKeyCode, UINT aScanCode)
 }
 #else
 BOOL nsWindow::OnKeyDown( UINT aVirtualKeyCode, UINT aScanCode)
-{
+{ 
   WORD asciiKey;
 
   asciiKey = 0;
@@ -3138,13 +3149,13 @@ PRBool ChildWindow::DispatchMouseEvent(PRUint32 aEventType, nsPoint* aPoint)
     case NS_MOUSE_LEFT_BUTTON_DOWN:
     case NS_MOUSE_MIDDLE_BUTTON_DOWN:
     case NS_MOUSE_RIGHT_BUTTON_DOWN:
-      SetCapture(mWnd);
+        SetCapture(mWnd);
       break;
 
     case NS_MOUSE_LEFT_BUTTON_UP:
     case NS_MOUSE_MIDDLE_BUTTON_UP:
     case NS_MOUSE_RIGHT_BUTTON_UP:
-      ReleaseCapture();
+        ReleaseCapture(); 
       break;
 
     default:
diff --git a/mozilla/widget/src/windows/nsWindow.h b/mozilla/widget/src/windows/nsWindow.h
index 13d35eb5bb0..e72f0d0ba34 100644
--- a/mozilla/widget/src/windows/nsWindow.h
+++ b/mozilla/widget/src/windows/nsWindow.h
@@ -86,7 +86,7 @@ public:
     NS_IMETHOD              IsVisible(PRBool & aState);
     HWND                    mBorderlessParent;
 
-
+    NS_IMETHOD              CaptureMouse(PRBool aCapture);
     NS_IMETHOD              Move(PRUint32 aX, PRUint32 aY);
     NS_IMETHOD              Resize(PRUint32 aWidth,
                                    PRUint32 aHeight,
diff --git a/mozilla/widget/src/xpwidgets/nsBaseWidget.cpp b/mozilla/widget/src/xpwidgets/nsBaseWidget.cpp
index 07e44a556e5..5af8c2e9771 100644
--- a/mozilla/widget/src/xpwidgets/nsBaseWidget.cpp
+++ b/mozilla/widget/src/xpwidgets/nsBaseWidget.cpp
@@ -217,6 +217,11 @@ void nsBaseWidget::BaseCreate(nsIWidget *aParent,
     }
 }
 
+NS_IMETHODIMP nsBaseWidget::CaptureMouse(PRBool aCapture)
+{
+  return NS_OK;
+}
+
 //-------------------------------------------------------------------------
 //
 // Accessor functions to get/set the client data
diff --git a/mozilla/widget/src/xpwidgets/nsBaseWidget.h b/mozilla/widget/src/xpwidgets/nsBaseWidget.h
index 499fd4e8b51..2a4d4fbf3eb 100644
--- a/mozilla/widget/src/xpwidgets/nsBaseWidget.h
+++ b/mozilla/widget/src/xpwidgets/nsBaseWidget.h
@@ -55,6 +55,7 @@ public:
     NS_IMETHOD              PreCreateWidget(nsWidgetInitData *aWidgetInitData) { return NS_OK;}
 
       // nsIWidget interface
+    NS_IMETHOD              CaptureMouse(PRBool aCapture);
     NS_IMETHOD              GetClientData(void*& aClientData);
     NS_IMETHOD              SetClientData(void* aClientData);
     NS_IMETHOD              Destroy();