window.browser = (function(){
  return  window.msBrowser      ||
          window.browser    ||
          window.chrome;
})();

var dashboardTabId = -1; // no id by default

browser.browserAction.onClicked.addListener((activeTab) => {
    if(dashboardTabId === -1){
        browser.tabs.create({url : 'dashboard/index.html'}, (tab) => {
            dashboardTabId = tab.id;
        });  
    }
    else {
        browser.tabs.update(dashboardTabId, {"active": true, "selected": true});
    }
});

browser.tabs.onRemoved.addListener((removetabid, removeInfo) => {
    if(dashboardTabId != -1 && removetabid === dashboardTabId){
        dashboardTabId = -1;
    }   
});