Thanks a lot! I just checked it out. It is not what I exactly meant, but at least now I have seen an example of spritefont.
In your 2nd example:
Let's say head1 and tail1 are a couple.
How would you check whether the head and the tail-sprite on screen match?
So: head1 and tail2 on screen: no match.
head1, tail1 on screen: match ("do something").
I am going to try something again with instance variables again. If I have something, I will post it.
If you could state all your requirements at once, I can help, otherwise it's just guessing