What an ordeal... I like to make everything I do on the web Mac compatible, even thought its not an official requirement at my job, I make it one. Not because I am a masochist, but because I love my Mac and my fellow mac users.
So there is a web app I work on that uses an alpha channeled PNG with 80% opacity to make popup boxes modal, so you can't really click thru them and do anything else in the app's background when they're up, kind of like an alert box. The alpha channeled PNG is an elegant way to achieve this because it's white and only 80% opaque, so you can still kind of see thru it to the map behind it so its not disorienting when the popup comes up. Nice.
But the alpha channeled PNG didnt seem to work in Safari, and just showed up as a block of solid white instead. Which was irritating because everything I found on Apple's website about this purported that Safari fully supported PNG's, including the alpha channel... So after poking around for a bit, I finally decided to stop looking for Safari documentation and go straight to the source --> Konqueror, the rendering engine under Safari's hood. Finally I found a post from a developer in one of their forums begging the engineers to support PNG's, to which the engineer replied that they *did* support PNG's. To which another user helpfully posted, "I think the author was talking about full PNG support ... last time I checked the alpha channel in PNG wasn't supported."
To which other engineers responded by claiming full support had been implemented. One engineer even posted a PNG that displayed the evasive transparency in Safari, and explained he had made the PNG in GIMP. So I experimented myself and made a few PNG's in GIMP and *magically* they worked. My Photoshop PNG's still didnt work, but my GIMP one sure did, well sort of. The color values are slightly off.
I guess Apple's QA department was asleep at the wheel on this one. Or maybe they're all on Unix boxes (?!). Either way, make your semi-transparent PNG's in GIMP if you want 'em to work on Safari < 2.0.
