passed nothing back from the subroutine? This seems doubtful...

You don't return from a callback :) unless the caller expects you to return ... Tk usually doesn't expect return values from callbacks ... op either needs to stuff $tura into a widget, or another object, which is done by giving it the object/widget as reference, or making the object/widget a global

this means

sub tura { ... $globals{tura} = $tura;

... -browsecmd =>  [ \&tura, \%globals ],   ...
sub tura { ... my( $globals_ref ) = @_;  $globals_ref->{tura} = $tura;
+ 

... -browsecmd =>  [ \&tura, \$original_tura ],   ...
sub tura { ... my( $tura_ref ) = @_;  $$tura_ref = $tura;
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