Hi John,
We have an RFE for this (see link below), and I added a +1 from you on it.
https://github.com/orbeon/orbeon-forms/issues/2390For now, if you search for <fr:tabbable> in the source, you can see how it is used in the Form Builder dialogs. And of course, if anything isn't clear, feel free to ask here.
https://github.com/orbeon/orbeon-forms/search?utf8=%E2%9C%93&q=%22fr%3Atabbable%22&type=CodeAlex
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