rem: messenger.saveAttachment(this.contentType, this.url, encodeURIComponent(this.displayName), this.uri, this.isExternalAttachment); 
add: if (this.isExternalAttachment) internalSave(this.url, null, this.displayName, null, this.contentType, false, "SaveAttachmentTitle", null, null); else messenger.saveAttachment(this.contentType, this.url, encodeURIComponent(this.displayName), this.uri, false); 
context: createNewAttachmentInfo.prototype.saveAttachment = function saveAttachment(){  messenger.saveAttachment(this.contentType,                            this.url,                            encodeURIComponent(this.displayName),                            this.uri,                           this.isExternalAttachment);}
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/c67c03a3fc635505d328b7563f89ccd4211ffab2/msgHdrViewOverlay.js/clean/mailnews/base/resources/content/msgHdrViewOverlay.js