Using autowidth on buttons type icons will make a large right padding on the button when skin is “Material”
This can be annoying when there is lot of buttons. And It does not display well the button on the right because it is not aligned with the right border.
This problem was existing in version 4.0 but it is amplified since upgrade to version 4.2
Try this snippet : http://webix.com/snippet/4b697d91
See the result with “Material” skin and “Flat” skin