This is the enhanced version of the Halo ButtonSkin that has been customized to support four numeric
values in the corner, a more configurable border, and also a large number of colors in the gradient
(limited by 15 in ProgrammaticSkin.drawRoundRect), individually specified for up, over, etc states..
<p>
<ul>
<li>
corner-radii: An array of four numeric values indicating the four corner radii [TL, TR, BR, BL]
</li>
<li>
fill-colors: An array of colors to use for the fill state gradient (of arbitrary number)
</li>
<li>
selected-fill-colors: An array of colors to use for the fill gradient of the selected state.
</li>
<li>
over-fill-colors: An array of colors to use for the fill gradient of the over state.
</li>
<li>
disabled-fill-colors: An array of colors to use for the fill gradient of the disabled state.
</li>
<li>
down-fill-colors: An array of colors to use for the fill gradient of the down state.
</li>
</ul>
<ul>
<li>
fill-color-ratios: An array of values from 0 to 255 that indicate the position of the colors in the selection gradient.
Must match the cardinality of the fill-colors, or else a default will be used.
</li>
<li>
selected-fill-color-ratios: An array of values from 0 to 255 that indicate the position of the colors in the selection gradient.
Must match the cardinality of the fill-colors, or else a default will be used.
</li>
<li>
over-fill-color-ratios: An array of values from 0 to 255 that indicate the position of the colors in the over gradient.
Must match the cardinality of the fill-colors, or else a default will be used.
</li>
<li>
disabled-fill-color-ratios: An array of values from 0 to 255 that indicate the position of the colors in the disabled gradient.
Must match the cardinality of the fill-colors, or else a default will be used.
</li>
<li>
down-fill-color-ratios: An array of values from 0 to 255 that indicate the position of the colors in the down gradient.
Must match the cardinality of the fill-colors, or else a default will be used.
</li>
</ul>
<ul>
<li>
border-colors: An array of color values for the border in the up state. (defaults to border-color).
</li>
<li>
over-border-colors: An array of color values for the border in the up state. (defaults to theme-color derived)
</li>
<li>
selected-border-colors: An array of values indicating the color of the selected border. (defaults to over-border-colors)
</li>
</ul>
<ul>
<li>
border-thickness: The thickness of the border.
</li>
<li>
border-alpha: The alpha value of the border.
</li>
<li>
disabled-border-alpha (defaults to 50% of border-alpha).
</li>
</ul>
</p>