Well, to make it short and sweet, no, there is no wysiwyg editor that adds a bunch of proprietary stuff to your code that ensures it'll only run on Windoze, that's a M$ thing
Actually, Netscape Composer comes built in. It's simple, but effective if you're not doing crazy stuff.
For about 8million others, check out freshmeat.net and type HTML wysiwyg or HTML editor into the search thing. It'll probably come up with a bunch of stuff.
...Isn't Bluefish a decent one? I only worked with it for a short while, and it was a while ago, but I think it was ok.
Also, no editor will be able to edit the site 'in place'. It has to be able to pull it down to edit it, AFAIK. This is because they can't write code and perform a 'save' function across the internet. It needs to be saved to retain the changes. If FrontPage seemed like it was doing that, it was all smoke and mirrors. FrontPage keeps a copy of everything you did locally, including changes. Sorta like a built-in CVS. A lot of editors, though, have built in ftp functionality, so don't fret.
Oh yeah, if you used FrontPage to put a theme on your site, I'm pretty sure your screwed if you wanna edit stuff on anything but a windoze box, but I could be mistaken.
Keep this in mind though:
Created on Linux w/ HTML = it'll run anywhere, can be moved to anywhere, edited anywhere, and uploaded to any kind of server, and it'll run.
Created by an M$ tool = it will run on M$, can only be moved to M$ boxes, and uploaded to M$ servers, and it has a decent chance of running bug free.
I tried....
