--- a/embedding/base/nsIWindowProvider.idl
+++ b/embedding/base/nsIWindowProvider.idl
@@ -53,17 +53,17 @@ interface nsIURI;
 /**
  * The nsIWindowProvider interface exists so that the window watcher's default
  * behavior of opening a new window can be easly modified.  When the window
  * watcher needs to open a new window, it will first check with the
  * nsIWindowProvider it gets from the parent window.  If there is no provider
  * or the provider does not provide a window, the window watcher will proceed
  * to actually open a new window.
  */
-[uuid(5119ac7f-81dd-4061-96a7-71f2cf5efee4)]
+[scriptable, uuid(5119ac7f-81dd-4061-96a7-71f2cf5efee4)]
 interface nsIWindowProvider : nsISupports
 {
   /**
    * A method to request that this provider provide a window.  The window
    * returned need not to have the right name or parent set on it; setting
    * those is the caller's responsibility.  The provider can always return null
    * to have the caller create a brand-new window.
    *