Bug in Tk::Dervied.pm

Sorry, but I am not a frequent user of perl/Tk and could not find a
better way of reporting this problem (email to the address for Nick in
the FAQ is returned 'user unknown').

There is a small coding slip in Derived.pm line 94 (version 4.010)

foreach my $key (%$widget)

should be

foreach my $key (keys %$widget)

This leads to all kinds of strange errors, none near this particular
statement.  The amazing thing, however, is how often the code runs with
no symptoms of any problem at all!