tightly packed portable version of this code

--------------------------------------------------------

#!/usr/bin/env bash

cat <<EOF | /usr/local/bin/wish

package require Tk

pack [button .b -text {Push Me} -command {

    tk_messageBox -message {hello, world}

}]

EOF

--------------------------------------------------------

Of course doing it directly in Tk Tcl would be even more portable, readable, simple and smarter and easier to deploy/maintain.

And at the opposite of gtk team tk team does not breaks API for the pleasure of being more right than the users.

So it would be a win-win-win situation to use Tk/Tcl instead of gtk3.