How can I add a column for ZoteroPane.itemsView ?

Hi, I'm an extension developer. I've tried these code and not work:

ZoteroPane.itemsView.props.columns.push({
dataKey: "mycol",
defaultIn: new Set(["default", "feed"]),
label: "mycol",
flex: 1,
zoteroPersist: new Set()
})

By the way, I can add an element after the title of a row:

const title = $('#item-tree-main-default-row-6').find('.title');
title.after('666')
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