#!/usr/bin/perl

 my @b;
 for my $i ( 1 .. 5 ) {
     $b[$i] = $top->Button(
         -text=>$i,
         -command=> &mybuttons($i),
                    ^^^^^^^^^^^^^^^^
                        WRONG

# Stephen O. Lidie writes:                       
#   -command expects a *code reference*, that shall, at some future time, 
#   execute.  You've called for an immediate execution, which in theory could 
#   return a code ref, but doesn't here. 

#   Ya'all all are skrting around a closure, which may be created in various 
#   ways, all detailed in you know what. 

#  Try: 

-command => sub {&mybuttons($i)}

#or maybe: 

-command => [\&mybuttons, $i]