I can't be certain (who can?:-), but I'd guess you've hit on browser specific functionality.

BTW, you probably want to rewrite = ~m/^.*(\\|\/)(.*)/ as =~ m,^.*(:?\\|/)(.*), or even =~ m,^.*[\\/](.*) - thus incorporating observations mode elsewhere on this thread and also the fact that m/^.*(\\|\/)(.*)/ will return the path to the file as $1 and the file itself as $2.