A button may have 3 different appearances, depending on the map size and the number of other controls on the map. On a small map, the button displays only the icon; on a medium-size map, the text of the button is shown; on a large map, the button icon is displayed with the text. You can lock the button in any size or you can specify only the icon or text only.
By default, maximum button width is 90 pixels. If your button contains a long text, you should set it to the desired maximum size using the maxWidth option.