Weird bidi behavior?

Can somebody explain the bidi behavior of Case 2 at
http://www.sw.it.aoyama.ac.jp/2008/pub/bidi-test.html ?
The only difference between Case 1 and Case 2 is that
Case 2 uses dir='ltr' on the green <span>.

Regards,    Martin.


#-#-#  Martin J. Du"rst, Assoc. Professor, Aoyama Gakuin University
#-#-#  http://www.sw.it.aoyama.ac.jp       mailto:duerst@it.aoyama.ac.jp