width: autopx; in composer.php

While hooking into the button function from composer.php I noticed that the default for button_width is defined by:

$prefix . '_width' => 'auto'

But the function does the following, producing an incorrect width: autopx

        if (!empty($options[$prefix . '_width'])) {
            $a_style .= ' width:' . $options[$prefix . '_width'] . 'px;';
            $table_style .= 'width:' . $options[$prefix . '_width'] . 'px;';
        }