rem: unassertMIMEStuff(MIME_URI(this.mimeType), "fileExtensions", aExtensionString); 
add: unassertMIMEStuff(MIME_URI(this.mimeType), "fileExtensions", aExtensionString.toLowerCase()); 
context:   removeExtension: function (aExtensionString)  {    unassertMIMEStuff(MIME_URI(this.mimeType), "fileExtensions", aExtensionString);  },
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/1c41377183c86f3b4371c76a2d1a7c2529e8e6b8/overrideHandler.js/clean/xpfe/components/prefwindow/resources/content/overrideHandler.js