load) =>
            parent.postMessage({ ...payload }, ev.origin)
          const send_reply = (payload) => send_message({ ...payload, cmd_id })
          const send_ok = () => send_reply({ action: 'cmd_ok' })
          const send_error = (message, stack) =>
            send_reply({ action: 'cmd_error', message, stack })

          if (action === 'theme') {
            const themeSheet = document.getElementById('pinceau-theme')

            if (themeSheet && ev.data.args.theme) themeSheet.innerHTML = ev.da