This is a real bummer and is definitely due the latest Safari 5.1.7 and it's associated Web Kit framework that does most of the rendering that another thread mentioned was the cause of their printing problem with TF for Mac.
I installed the Safari 5.1.5 on my SL iMac May 5, and sure a h'll now, when I open any of my completed saved tax files or a new one, all the (&^&&* text fields are black and the entered text is green when clicked to view which BTW, looks the same as my Appearance set highlight color. Thanks a lot Apple.
I also checked and booted onto my Leopard 10.5.8 volume with Safari 5.0.6 version and all the FTforMac tax files open and display properly with proper black text on a white background.
So I thought I'd try installing an older copy of Safari. but the SL OS says no way!!!
Besides, it seems that the web kit stuff would have to be replaced as well:
"Safari normally uses the Web Kit framework found inside Mac OS X to render web pages and execute javascript. This means that if you preserve an old version of Safari to run it on a newer version of Mac OS, it will use the newer Web Kit found in the system and you will get the same results as with the newer version. Thus, you would normally need a separate installation of Mac OS X for each version of Safari you want to test a website into."
So I guess even using Pacifist won't help.
I did come across some possible suggestions, but haven't tried - yet!! :
Restore previous Safari version from .SafariArchive.tar.gz - Mac OS X Hints
Old Version of Safari for Mac Download - OldApps.com
and
feed://mac.oldapps.com/safari.php?feeds=rss
But THIS one
might work, they include the appropriate web kit stuff it seems. but they're pretty old versions:
Multi-Safari
Or maybe you can get access to and use a Mac or maybe a bootable clone that hasn't been updated with Safari 5.1.7 and use them!!
What a REAL Royal PITA Apple!!!