sub brscmd {
             my ($previous_index, $actual_index) = @_;
             my ($row, $col) = split ',', $actual_index;
             my ($sel, $js);

             $t->after( 'idle',  # <-- THE SOLUTION
                        sub{
                             my $sel = $t->curselection();
                             print "@$sel\n";
                             foreach $js (@$sel) {
                                print "[brscmd] actual
                                index <$actual_index> 
                                from curselection <$js>
                                last_button_key 
                                <$last_button_key>\n";
                             }
             }
        );
}