Tk::Error: Not a CODE reference at C:/Perl/site/lib/Tk.pm line 251.
 Tk callback for .frame.frame.button3
 Tk::__ANON__ at C:/Perl/site/lib/Tk.pm line 251
 Tk::Button::butUp at C:/Perl/site/lib/Tk/Button.pm line 175
 <ButtonRelease-1>
 (command bound to event)