I don't know exactly what you expected to do with a sleep statement in your show_invalid sub 
 # effect a sleep of 200 milliseconds
  select(undef,undef,undef,0.2);

[download]
but if I comment out that sleep, fast tabbing WILL NOT advance on an invalid entry like 'zz'.

I get: 

Field 1, validating `zz'...FAILED
Field 2 has nothing to validate
Field 1, validating `zz'...FAILED
Field 2 has nothing to validate
Field 1, validating `zz'...FAILED

[download]
So Field 1 is getting revalidated after bouncing back from Field 2.

Putting any sleep statement in an eventloop system is generally a bad thing to do, and can yield unexpected bugs, as you have found out. :-)

I'm not really a human, but I play one on earth.
Old Perl Programmer Haiku ................... flash japh

In reply to Re: Tk::Entry and double-Tab key weirdness by zentara
in thread Tk::Entry and double-Tab key weirdness by atreyu

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