I'm not sure what your calculations need to be, but would something like this give you any ideas?

#!/usr/bin/perl -w
use strict;
use Tk;
 
my @entries;
my $mw = MainWindow->new;
my $frame = $mw->Frame()->pack(-padx => 10,-pady => 10);
 
foreach my $i (0..2) {
   $entries[$i] = $frame->Entry(-relief => 'raised',
                            -text => "Entry $i")->pack(-side => 'left'
+);
 
   $entries[$i]->bind('<Enter>' => [\&sayHello,$i]);
   
   $entries[$i]->bind('<Leave>' => [\&sayGoodbye,$i]);
 }
 
 
 MainLoop;
 
 sub sayHello {
   my $w = shift;
   my $id = shift;
   $frame->grab;
   print "Hi, I am entry $id!\n";
 }

 sub sayGoodbye {
   my $w = shift;
   my $id = shift;
   $frame->grab;
   print "Goodbye, I am entry $id!\n";
 }
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