--- pm11142273.pl.~54~  2022-03-22 13:34:52.301454754 -0700
+++ pm11142273.pl       2022-03-23 06:39:44.750787662 -0700
@@ -5,7 +5,8 @@
 use Tk;
 
 my $additionalcheckbutton = 0;
-my @checkbuttonlabels = split /\n/, <<END;
+# NOTE 1a) wrap if text too long
+s/(.{20}) /$1\n/g for my @checkbuttonlabels = split /\n/, <<END;
 one
 two
 very long text entry for test purposes
@@ -28,7 +29,7 @@
 my @cbs = map
        {
        $leftframe->Checkbutton(
-               -text => s/.{20}\K /\n/gr, # NOTE 1a) wrap if text too long
+               -text => $_,
                -anchor => 'w',      # NOTE 1) align buttons with -fill x
                -variable => \$values[$n++],
                -command => \&addextra,