Choosing for different screens

<switch>
   <text src="joe-text-200" system-screen-size="200x100"/>
   <text src="joe-text-640" system-screen-size="640x480"/>
   <text src="joe-text-800-8" system-screen-depth="8" 
                             system-screen-size="800x600"/>
   <text src="joe-text-800-16" system-screen-depth="16" 
                             system-screen-size="800x600"/>
</switch>