tuned signature -- avoid intrusion of slightly odd Swing structures into pure Markup_Tree;
Cygwin
======
* http://www.cygwin.com/
* Mirror with many old versions (not setup.ini)
http://ftp.eq.uc.pt/software/pc/prog/cygwin
* Local snapshots:
http://isabelle.in.tum.de/cygwin (Isabelle2012)
http://isabelle.in.tum.de/cygwin_2013 (Isabelle2013)
* Quasi-component: "isabelle makedist_cygwin"