Minor Description
LinkButton's default renderer used to be able to wrap the text of its label (you can see the artifact of this in the LinkButtonDataRenderer constructor). Since the change to not support horizontally justified horizontal box panes, this no longer works. The reason that LinkButtonDataRenderer is a horizontal box pane is to accommodate the image and the text in the button data, but it means that the "fill" style won't constrain the width of the renderer's label.