Can I run Classilla on 7.x, 8.0 or 8.1?
No, for the same reasons as above; Classilla’s runtime depends on certain features of Mac OS 8.5 and higher such as ATSUI and Unicode support. Again, there has been some talk of disabling the portions of Classilla that depend on these features or backporting the needed OS libraries, but this work is unlikely to be done in the near future and such a modification would also severely limit its usefulness for multilingual pages. Likewise also, many of the Macintoshes limited to these OS versions have significant memory pressure and Classilla has never been particularly thrifty with RAM. In short, while such a “Classilla 7” is theoretically possible, a fair amount of work would be needed to get it mounted, it would not be as functional as standard Classilla, and it would detract from our top priority which is to be as compatible with modern websites as possible.
