changes:
2) Corrected the Java simulation to allow units (or to ask for the answer in mm) and to prevent the vernier scale from being unreadable.

done.
added mm in texts
made xmagnify = -10 , ymagnify = 0
found that mx and my is causing the weird behavior, made them -10 and 0 as well like xmagnify and ymagnify so that it loads at the centre of the simulation view!

the simulation is downloadable from the this post or
mirror here
http://dl.dropbox.com/u/44365627/lookangEJSworkspace/export/ejs_AAPTVernierCaliper.jar

enjoy!