I haven't delved into WHY this is broken, but here's a fix:
Download the latest draw2d
http://www.draw2d.org/draw2d/node/105
(I downloaded 0.9.19)
unzip, and find the folder withnamespace\single\
copy everything from there to:
(this is based on the windows all-in-one installation, folders will be different on other installations)
C:\Users\Me\OpenERP AllinOne\WEb\Python25\Lib\site-packages\openerp_web-5.0.6-py2.5.egg\openerp\static\workflow\javascript\draw2d\
overwrite the files already there.
Then download wz_jsgraphics.zip from
http://www.walterzorn.com/jsgraphics/js ... m#download
unzip and copy the wz_jsgraphics.js file to that last folder (the one that ends in draw2d\)
after doing that, mine worked again.