The screenshots don't reveal much. I don't know why. The difference is obvious. I've shown it to people here and they agree. Anyone reading this will have to take my word.
Screenshots are not a "photograph" of the screen contents, rather a screenshot captures the "code" that generates the screen image. In Apple's case that code is PDF. What image format are your screenshots in, PNG, PDF, TIFF, BMP, GIF, PSD, or what? If you don't know TinkerTool will tell you as well as easily switch screenshot formats. Try changing the screenshot format and see if the difference shows up. That is in fact a diagnostic that may help identify the source of your problem. By the way, as I recall I finally ended up deleting Helvetica Neue in either 10.5 or 10.6 because of various font issues which were cleared by deleting the font. Helvetica Neue was re-instlled in a subsequent OS X release and the problems in the font had been fixed.
I wonder if the graphics drivers in the ATI card is causing the problem, since that was causing kernel panics in Firefox. I doubt the graphics card is involved in rendering fonts.
Probably not directly, but they could be indirectly involved.
I continue to use Beyond Compare, a fine program, to analyze which files have changed from 10.6.7 to 10.6.8. I'm worried that the culprit will be some obscure file which I shouldn't change, like Ruby or Pearl or some framework or something in the Core system files. Quartz maybe. I noticed some Thunderbolt files which I could probably delete since I don't have a Thunderbolt monitor. I know better than to start deleting just to experiment. There are too many deep files whose purpose is unknown to me.
Unless you enjoy frequent reinstalling, stay out of the system files. You never know when one of those files is used by another part of the system or even an application. For example
Perl and
Ruby are powerful scripting languages that can be and are used in a wide variety of different applications.
FWIW although I have never moved any Font files out of /System/Library/Fonts I have used TinkerTool and other utilities to change the default system and application fonts since OS X 10.0 with no ill effect (unless I choose a font size that is too big to fit in the space allowed in some places).
ETA: Interesting that in recent OS Apple gave up on Helvetica altogether as a system font.
I just looked in /System/Library/Fonts on my system running MacOS 10.11.6 Beta (15G24b) and found Helvetica.dfont created 8/22/15, HelveticaNeue.dfont created 8/22/15, and NelveticaNeueDeskinterface.ttc also dated 8/22/15. so although it might not be the default Helvetica is still around as a system font. HelveticaNeue is an extra thin version of Helvetica. Its thinness allows more characters in a given space which is why Apple has chosen it. It fits the displays on iOS devices better than either of its predecessors Helvetica and Lucida Grande. Personally I prefer Lucida Grande as just a bit more readable, but that may be a factor of
elder eyes.
