http://x.cygwin.com/docs/ug/setup-cygwin-x-installing.html
- xinit (required, scripts for starting the X server: xinit, startx, startwin (and a shortcut on the Start Menu to run it), startxdmcp.bat )
- xorg-docs (optional, man pages)
- X-start-menu-icons (optional, adds icons for X Clients to the Start menu)
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