Constraining the width and height of the window to 640x480

profile/resources/pm.xul

@@ -2,7 +2,9 @@
 <?xml-stylesheet href="chrome://global/skin/xul.css" type="text/css"?>
 <?xml-stylesheet href="pm.css" type="text/css"?>
 
-<window
+<window 
+  width="640"
+  height="480"
   xmlns:html="http://www.w3.org/TR/REC-html40"
   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
   xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">