ruby--ruby/ext/tk/sample/tkhello.rb

require "tk"

TkButton.new(nil, 
	     'text' => 'hello',
	     'command' => proc{print "hello\n"}).pack('fill'=>'x')
TkButton.new(nil,
	     'text' => 'quit',
	     'command' => 'exit').pack('fill'=>'x')

Tk.mainloop