title: Cygwin gitk issue
body: <p>I have recently installed all of the X11 packages in the cygwin setup and now
  have is massive annoying error with not being able to see gitk. Everything was
  working perfectly well until I installed this stuff.</p>
  
  <p>Before I had this issue I didn't really note done any of the configuration I
  merely started xwinserver went to my branch and typed gitk and everything
  appeared.
  Now I have to put in my display as it claims the display is not set. I export my
  display settings check that it is set properly by running xclock which does
  appear. Then I get the issue:</p>
  
  <pre>
  1 [main] wish8.5 3436 child_info_fork::abort: data segment start: parent(0x4CF000) != child(0x67F000)
  Error in startup script: unknown color name "SystemButtonFace"
  while executing
  "winfo rgb . $c"
  (procedure "setui" line 3)
  invoked from within
  "setui $uicolor"
  (file "C:\cygwin\bin\gitk" line 11504)
  </pre>
  
  <p>Not got a clue what this is. I have seen a couple of relevant questions but no
  answers.</p>
  
  <p>Notes: I am using Windows 7 64 bit and using a Bash shell</p>
  
  <p>Update: I am still getting exactly the same error. This is really frustrating! I
  may just download Debian</p>