src/View/Helper/ListFilterHelper.php
public function filterActive()
    {
        $filterActive = (isset($this->_View->viewVars['filterActive'])
                        && $this->_View->viewVars['filterActive'] === true);

        return $filterActive;
    }
public function filterActive()
    {
        $filterActive = (isset($this->_View->viewVars['filterActive'])
                        && $this->_View->viewVars['filterActive'] === true);

        return $filterActive;
    }
Determines if any ListFilter parameters are set

@return bool