If the DISPLAY environment variable is set, the test_tcl test
'testLoadTk' gives a traceback.  In the same circumstance, test_tk and
test_ttkguionly display the error and are skipped.  Although this is a
nit rather than a problem, for consistencies sake I think the testLoadTk
test should also be skipped rather than show up as a failure.  I've
attached a patch against the trunk that does this, with the caveat that
it is an individual testcase being skipped so it doesn't get recorded in
the 'skipped tests' summary.  I don't think this is a problem since
test_tk will likely show up in the skipped tests if this one is skipped,
and also there are circumstances in which testLoadTkFailure is skipped
completely silently.

Perhaps the real problem is that the tk tests should be in test_tk
instead of test_tcl?