Button caption text alignment in XML

To those who have edited the .twb file, were you able override the button text alignment? I'm trying to make it right aligned.

I've tried adding <format attr='text-align' value='right' />

I've tried fontalignment='2'

But, to no avail.

<button action='tabdoc:goto-sheet window-id="{F9922688-A3CF-4B92-804A-45CD2DC66223}"' button-type='text'>

         <button-visual-state>

          <caption>Introduction</caption>

          <tooltip-text>Introduction</tooltip-text>

          <button-caption-font-style fontcolor='⌗002f6c' fontname='Arial' fontsize='11' />

          <format attr='background-color' value='⌗ebf3ff' />

          <format attr='border-style' value='solid' />

          <format attr='border-width' value='1' />

          <format attr='border-color' value='⌗ffffff' />

         </button-visual-state>

        </button>