I certainly do NOT want other visitors experieicing that, but I suspect you wouldn't want it either..... You didn't comment about your theme tester site. As I said, it uses transparent pngs, have you had anyone report problems viewing that site? Also, the s9y emoticons and the s9y logos are pngs, so ANYONE running s9y, who happens to make use of PNGS, would be in the same position, wouldn't they?
Now - the only thing I wonder about is the fact that all of my backgrounds are pngs (with the exception of page background, ie outside the mainpane). So, I have pngs on top of pngs, if you will. Wonder if that could be an issue. Nothing stopping me from re-generating everything as GIF other than the fact that png produces much nicer results.
I read some interesting stuff here: http://en.wikipedia.org/wiki/GIF
"In December 1994, after Unisys discovered that the newly-popular (GIF) file format used LZW compression, they announced that they would be seeking royalties on that patent; all commercial programs capable of producing GIF files would be required to pay a license fee to Unisys."
That one would suggest a program shipping with bundled GIF images (like emoticons) would not present a problem - they are merely using the image, not PRODUCING the image.
"Unfortunately many people are under the misconception that Internet Explorer does not support transparent pngs. This results from confusion of alpha channel transparency (which GIF does not offer) with binary transparency (which Internet Explorer supports for both GIF and PNG images)."
This one seems to completely contradict any problems with transparent pngs.
On June 20, 2003, the United States patent on the LZW algorithm expired, which means that Unisys and Compuserve can no longer collect royalties for use of the GIF format in that country. Those bothered with the patent enforcement dubbed this day GIF Liberation Day. The equivalent patents in Europe and Japan expired on June 18 and June 20, 2004 respectively, with the Canadian patent following on July 7.
IBM has also patented the LZW algorithm, but has never enforced this patent. According to the Free Software Foundation that patent will expire on August 11, 2006 in the United States.
Looks like this entire issue will be a moot point in a few months anyway.
But that still leaves me with a potential problem for visitors... do I scrap all things png???