Im not entirely positive which version made the switch, but I think it was the last one ( or 026). They made a switch from it being based on the old TCL version 800 to the later version 804. If you look on cpan, PerlTk went from version 800.025 to 804.026 in 1 step. I'm sure that was where it changed the behavior you describe. I guess you could check the Changelogs. I know it breaks alot of old scripts,(I've had to search and replace a few myself) but it does "tightenup" the code. The old method, let you get away with some "sloppy options".