Hi Kevin, Although we should be able to make 64-bit Mac Chimera run on Mac OS 10.5 we do not have the time to do this given our many other priorities. The trouble is that Chimera depends on about 40 third-party libraries that we automatically build along with Chimera. Making the build scripts for those libraries compile 64-bit instead of the default 32-bit on Mac OS 10.5 is expected to be a significant bit of work. On Mac OS 10.6 the compilers use 64-bit by default so the third-party libraries don't need any special configuration to get 64-bit binaries. One of the competing priorities is working around 20 bugs found so far in Tk Cocoa that effect Chimera http://plato.cgl.ucsf.edu/trac/chimera/ticket/7931 I have reported many of these Tk Cocoa bugs but it does not look like the Tk Cocoa developer Daniel Steffens will not have time to work on these in the short term, so I have to find ways to patch the problems within Chimera. Tom
For the 32-bit versus 64-bit Chimera Cocoa you should use 64-bit if you have Mac OS 10.6 (Snow Leopard) or 32-bit for older Mac OS versions. We don't offer 64-bit Mac Chimera on Mac OS 10.5 or older Mac OS versions.
Any reason the 64-bit Cocoa version isn't supported on 10.5? Tk-Cocoa works fine on 10.5.