On the demo page, FCKeditor is broken in Firefox 2.0.0.5, and Opera 9.22. In Firefox, only a few of the icons are loading. In Opera, no toolbars are present.
Well, it wasn't a matter of the version, but of the fact that I usually have my cache disabled (aids in viewing changes when I'm developing sites). Turning the cache on fixed everything.
Re: Demo page not working in Firefox or Opera
Re: Demo page not working in Firefox or Opera