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: 8395	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/8395/68b5ab8b21e6601a7cb0549e0994022c98fbc57f/msgHdrViewOverlay.js/clean/mailnews/base/resources/content/msgHdrViewOverlay.js