Tk::Error: bad text index "0" at C:/Program Files (x86)/Perl/lib/Tk.pm line 252.
 Tk callback for .frame.frame.rotext
 Tk callback for .button1
 Tk::__ANON__ at C:/Program Files (x86)/Perl/lib/Tk.pm line 252
 Tk::Button::butUp at C:/Program Files (x86)/Perl/lib/Tk/Button.pm line 111
 <ButtonRelease-1>
 (command bound to event)