[rwmj]

One genuine problem was the you could send snippets of code to any Tcl/Tk program running on the same X server and it would execute them. Obviously X isn't the most secure of systems and you should trust your X clients, but this made it very easy if you could persuade someone to run a "command line" program. I wonder if that was fixed?

[cmacleod4]

This is something to be aware of. It can be guarded against, see https://www.tcl-lang.org/man/tcl/TkCmd/send.htm#M9 .

[rwmj]

To be fair, it is a pretty cool feature.