X failures if two users

[luke dot kendall at cisra dot canon dot com dot au]

If two people use the same machine, and the first starts X, the second
person can't start X unless they have administrator rights.

Cygwin sets /tmp to have mode drwxrwxrwt which means ordinary users
can't remove /tmp/XWin.log if it's owned by someone else.  So
subsequent attempts to start X fail because it can't write the log file.

My suggestion would be for X to create the file called
/tmp/XWin.log.$USER

luke

PS:

Note that unlike Unix, it is possible for a user to remove a file that
some other user created in a directory with the above permissions,
provided they have administrator privileges on a machine.