Backend\Modules\Extensions\Actions\ThemeTemplates::loadForm PHP Метод

    private function loadForm()
    {
        // create form
        $this->frm = new BackendForm('themes');
        // create elements
        $this->frm->addDropdown('theme', $this->availableThemes, $this->selectedTheme, false, 'form-control dontCheckBeforeUnload', 'form-control dontCheckBeforeUnload');
    }