button

Tcl/Tk

#!/usr/local/bin/wish4.2

button .b -text "Hello World!" -command exit
pack .b -fill x

ruby/Tk

#!/usr/local/bin/ruby

require "tk"

TkButton.new {
  text 'Hello World!'
  command 'exit'
  pack('fill' => 'x')
}

Tk.mainloop