For my Notifier Plugin I wrote a PHP-function that got the active URI-scheme for the panel.
The output was matched to the folder-preference in the config-file, so the plugin “knew” the panel-dir was active…
config.php
function activeDIR($url)
{
substr($url,-1) != '/'?$url.= '/':$url = $url;
$path = parse_url($url, PHP_URL_PATH);
$pathTrimmed = trim($path, '/');
$pathTokens = explode('/', $pathTrimmed);
if (substr($path, -1) !== '/')
{
array_pop($pathTokens);
}
return end($pathTokens);
}
if(c::get('kirbyNotifierPanel') == activeDIR($_SERVER['REQUEST_URI']))
{
/* panel is active */
}