Adding hbox and vbox. Not used. Does not affect build.

xpfe/global/resources/content/xul.css

@@ -97,6 +97,13 @@ iframe {
 
 /******** Box *******/
 
+hbox {
+  behavior: url(chrome://global/content/xulBindings.xml#hbox);
+}
+
+vbox {
+  behavior: url(chrome://global/content/xulBindings.xml#vbox);
+}
 
 /******* ToolBox & ToolBar *******/
 

xpfe/global/resources/content/xulBindings.xml

@@ -5,6 +5,12 @@
    xmlns:html="http://www.w3.org/TR/REC-html40"
    xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
   
+  <binding id="hbox" extends="xul:box"/>
+
+  <binding id="vbox" extends="xul:box">
+    <content orient="vertical"/>
+  </binding>
+
   <binding id="thumb" extends="xul:box">
     <content>
       <xul:spring flex="1"/>