Add sticky option on group
The web has this option that we use already on some element like the toolbar. I think it will be great to allow this option on group so we could have sticky="top" or sticky="bottom". It will only be available for sao because GTK does not have such tool. And such feature is useful for small screen which is more often the use case for sao than tryton.
For example, it could be used on groups that contains button or links.