add: if (event.button != 0) return;  
context: function AttachmentBucketClicked(event){  if (event.originalTarget.localName == 'treechildren')    goDoCommand('cmd_attachFile');}
meta: 10234	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/10234/2a328ff4edcbecff014e14307928cae14409a903/MsgComposeCommands.js/clean/mailnews/compose/resources/content/MsgComposeCommands.js