="doc"><p>Specifies whether the display object is opaque with a certain background
color. A transparent bitmap contains alpha channel data and is drawn
transparently. An opaque bitmap has no alpha channel(and renders faster
than a transparent bitmap). If the bitmap is opaque, you specify its own
background color to use.</p>
<p>If set to a number value, the surface is opaque(not transparent) with
the RGB background color that the number specifies. If set to
<code>null</code>(the default value), the display o