When you create a button with an icon type, the icon is not centered, but 4 pixels to the left.
https://snippet.webix.com/2wzgef1m
Hello,
Button with an iconButton type should be with left padding, because this type is used with a label which is right of the icon. The icon type is also can be used with a label.
https://snippet.webix.com/g308ipwz
https://docs.webix.com/desktop__button.html#buttontypes
If you need only an icon, so please use view:“icon”
Or you can center the icon with the help of CSS in the sample which you sent
Like this: Code Snippet