- when folding/unfolding center new diagram element in the centre of the   old element
- when folding/unfolding center new diagram element in the centre of the
  old element


git-svn-id: 5a686552d234fe730d510dd4df126b9e41dc51f2@344 a8418922-720d-0410-834f-a69b97ada669

amolenaar/gaphor,amolenaar/gaphor