Font handling in OS X 10.5 is supposed to be better overall. So far, I've noticed Apple has moved the per user and system font caches to /tmp, which is probably a good move. 10.4.x didn't automatically purge font caches, which caused problems for folks who happened to activate and deactivate tons of fonts on a regular basis.

Another wrinkle is that the system has gotten more vigilant about keeping the HelveticaNeue.dfont and Helvetica.dfont versions firmly planted in the /System/Library/Fonts folder, as some Apple apps rely on their existence.

That's nice, but what about when you need to activate a postscript or opentype version of one of those fonts? Sorry… the system will complain.

If you delete the fonts from the System fonts folder, they'll pop right back. Shazaam!

What to do?

First, open Font Book, even if you don' use it for font management. Uncheck the options for "Automatic font activation" and "Alert me if system fonts change."

Then, you'll need to do some surgery.

On the command line, cd to:

/System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/ATS.framework/Versions/A/Resources/ProtectedFonts/

You can move, delete, or compress the Helveticas in that folder. I chose to compress and leave them there with:

sudo tar cfvz Helvetica.dfont.tar.gz Helvetica.dfont
sudo tar cfvz HelveticaNeue.dfont.tar.gz HelveticaNeue.dfont
sudo rm HelveticaNeue.dfont Helvetica.dfont

Then do the same to the Helveticas in /System/Library/Fonts. It's probably fine to leave the compressed archives there, but be sure to delete the fonts.

Once that's out of the way, copy your T1 or opentype versions in /Library/Fonts and log out or restart.

The system shouldn't complain any more, and you'll have your fonts active when needed.