if ABIWord uses a standard makefile and config files as most
opensource projects do, then compiling it on the mac should be no
problem. Of course, it's a matter of compatibility with libraries
and such as to whether it will actually work or not once it's
compiled, but that's something you won't know until you give it a try.
As far as whether it will be compatible with vo or not, I'd highly
doubt it, since it's not written in cocoa, but in regular C, and
won't have the benefits of apple frameworks and such, so even if it
can be made to work on OSX, I'd be very surprised if it works with
voice over out of the box. Though, it is possible it will work well
enough to be of use. Only way to know is to try it.
