I agree Phil. I am one of the many who ask for a native version for OSX every time I get a chance.
More and more people are switching to macs all the time. It was a big decision for me to switch but one I don't regret in the least (then again I had already made the switch to Linux from Windows 5 year prior so OSX wasn't as big a change for me). One of the first things I did before I switched was to make sure Slickedit was available. I assumed it was native, bought my mac and was sorely disappointed to see it was X11 based. But at least it is available.
Anyway, I do agree with you that SE needs to make a native version, because people are switching towards macs. As more coders move, there will be more incentive for mainstream people to move. And mainstream people that are talked into it by the Apple ads, or other people that have changed, will start to demand more and more software. Either way, I think it isn't a bad choice for SE to do a native version. Being a C/C++ programmer though, I know the amount of work it would probably take to get SE ported to native and that could be daunting if the mac user market isn't there to justify the time yet.
Oh, also I was premature in the fact that SE was working well with the new Xquartz (r11) and leopard. After using it for a bit, it started crashing on me all the time. Now I can't get it to run for more than 5 min before it crashes. So I fink'd fluxbox and use that as my window manager. Everything has been good for over a week now. So for other users having major probs, try installing fink and try a different window manager. It's a lot of hoops to jump through to get SE working, but I know I'm about 1/2 as productive without it, so it's probably worth the time to get it working.
