$form = $this->_formFactory->create();

        $fieldset = $form->addFieldset('base_fieldset', ['legend' => __('Widget')]);

        $fieldset->addField(
            'select_widget_type',
            'select',
            [
                'label' => __('Widget Type'),
                'title' => __('Widget Type'),
                'name' => 'widget_type',
                'required' => true,
                'onchange' => "wWidget.validateField()",
                'options' => $this->_getWidgetSelectOptions(),
                'after_element_html' => $this->_getWidgetSelectAfterHtml()
            ]
        );

        $form->setUseContainer(true);
        $form->setId('widget_options_form');
        $form->setMethod('post');
        $form->setAction($this->getUrl('adminhtml/*/buildWidget'));
        $this->setForm($form);