fieldset width auto

form elements fieldset width is automatically adjusted.
https://snippet.webix.com/w9roqhqk

but tabview cells elements filedset width is full tabview.width
https://snippet.webix.com/6x7i9itz

I am curious how to make the width of the filedset automatically adjust as in the form in the tabview.

Include the form in cols as well Code Snippet