Comment clarification from bug 347426, r+sr=bzbarsky

docshell/base/nsIContentViewer.idl

@@ -88,7 +88,9 @@ interface nsIContentViewer : nsISupports
    * Attach the content viewer to its DOM window and docshell.
    * @param aState A state object that might be useful in attaching the DOM
    *               window.
-   * @param aSHEntry The history entry that the content viewer was stored in
+   * @param aSHEntry The history entry that the content viewer was stored in.
+   *                 The entry must have the docshells for all of the child
+   *                 documents stored in its child shell list.
    */
   void open(in nsISupports aState, in nsISHEntry aSHEntry);