$viewButtonIcon
$viewButtonIcon : string
## Bootstrap button column widget.
Used to set buttons to use Glyphicons instead of the defaults images.
renderButton(string $id, array $button, integer $row, mixed $data)
### .renderButton()
Renders a link button.
| string | $id | the ID of the button |
| array | $button | the button configuration which may contain 'label', 'url', 'imageUrl' and 'options' elements. |
| integer | $row | the row number (zero-based) |
| mixed | $data | the data object associated with the row |