/** This script is run whenever the devtools are open. In here, we can create our panel. */ function handleShown() { console.log("panel is being shown"); } function handleHidden() { console.log("panel is being hidden"); } /** Create a panel, and add listeners for panel show/hide events. */ browser.devtools.panels.create( "My Panel", "icons/star.png", "devtools/panel/panel.html" ).then((newPanel) => { newPanel.onShown.addListener(handleShown); newPanel.onHidden.addListener(handleHidden); });