use Data::Dumper;
use Tk;

my $foo = '%h = (foo => q{bar}); \%h';
my $mw = MainWindow->new()->bind('<Return>', [\&foo, $foo]);
  
MainLoop();

sub foo {
    my (undef, $foo) = @_;  
    my $retval = eval $foo;
    print Dumper $retval;
}