<command arg="-root"/>
+ <video href="http://www.youtube.com/watch?v=BxGHUFvI2Zo"/>
+
<number id="delay" type="slider" arg="-delay %"
_label="Frame rate" _low-label="Low" _high-label="High"
low="0" high="100000" default="25000"
Escher's "Impossible Cage", a 3d analog of a moebius
strip, and rotates it in three dimensions.
-http://en.wikipedia.org/wiki/Maurits_Cornelis_Escher
+https://en.wikipedia.org/wiki/Maurits_Cornelis_Escher
Written by Marcelo Vianna; 1998.
</_description>