If I understand what you are trying to do, You could probably just hold off on setting your commands and use 'configure', like this:

$pgl->Label(
        -text => 'Project',
        -justify => 'right',
        -width => '20')
  ->grid(
     $pr_list = $pgl->BrowseEntry(
                      -variable => \$state->{prSrcName},
                      -width => '20'),
     -sticky => 'w', -pady => '20');

$pr_list->configure(
            -browsecmd => \&doGetProject,
            -listcmd => [ \&doLoadPr, $dbh, $pr_list ]
           );
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