in reply to Re^2: call subroutine if scalar is changed
in thread call subroutine if scalar is changed

You're changing the value before the main loop has been entered. Modify the final paragraph to 
$mw->after(1000, sub {
    print "name is $name\n";
    $name = "bar";
    print "name is $name\n";
});
MainLoop;

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map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]

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