Dear all,

after (finally) installing the minimals,
the  zip with the figures TeXs as expected  with MKII and MKIV.

Now, in MKIV I notice another issue. I use the \hideblocks mechanism  
to hide and reuse answers and get an error message (Undefined control  
sequence) in MKIV while everything is fine
in MKII.  I am attaching a sample file.

Thanks for all the help!

Matthias