To reproduce the bug, add 19 to the list of standard examples in examples/tk/standard_examples.in and run the test_tk_standard_examples target in
the build tree or installed examples tree. The error message that is produced by example 19 with tkdemos.tcl and plserver is is
"invalid command name "plslabelfunc". I assume this is some bit-rot generated by the implementation of plslabelfunc and its use in standard example 19.