TCA:

tca.php

‘config’ => array (
‘type’ => ‘select’,
‘form_type’ => ‘user’,
‘userFunc’ => ‘user_categroy_tree->displayCategoryTree’,
‘treeView’ => 1,
‘size’ => 1,
‘autoSizeMax’ => 20,
‘minitems’ => 0,
‘maxitems’ => 2,
‘foreign_table’ => ‘tx_extnews_category’,
)

ext_tables.php

if (TYPO3_MODE == ‘BE’)    {
include_once(t3lib_extMgm::extPath($_EXTKEY).’tx_categorys_viewtree.php’);
}

tx_categorys_viewtree.php下载

FLEXFORM与TCA配置相同

效果图：