If Xwin.exe is started with -silent-dup-error flag and a second instance of Xwin.exe is also started with the -silent-dup-error flag a pop-up notification shows up with fatal errors. The output in the terminal (with -silent-dup-error flag) is the same as shown below with the -v flag.
==================================================================== Xwin -v > bugreport Welcome to the XWin X Server Vendor: The Cygwin/X Project Release: 1.17.1.0 OS: CYGWIN_NT-6.1 Productie 1.7.35(0.287/5/3) 2015-03-04 12:09 x86_64 OS: Windows 7 Service Pack 1 [Windows NT 6.1 build 7601] (Win64) Package: version 1.17.1-2 built 2015-02-23 XWin was started with the following command line: Xwin -v (EE) Fatal server error: (EE) Server is already active for display 0 If this server is no longer running, remove /tmp/.X0-lock and start again. (EE) Fatal server error: (EE) Cannot move old log file "/var/log/xwin/XWin.0.log" to "/var/log/xwin/XWin.0.log.old" winDeinitMultiWindowWM - Noting shutdown in progress -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple