Paxx dixit: 'No applications are truly cross platform. What I mean is take the same version of Office, or Photoshop or Dreamweaver or heck Windowblinds, and install it on a Mac, on a PC or on a Linux machine'
Yes, it's true. I use Internet Explorer on Mac and it's very different than Windows version (ai interface and rendering pages, specially Javascripts).
I 'use' Photoshop on both platforms too, and both versions are very similar (including responsiveness when you click layer effects panel); the major difference is the floating windows on Mac platforms and some direct shorcuts (ctrl instead command/apple).
I purchassed some time ago Animation:Master (a 3d program with Mac and Windows versions into the same cd, using the same license). In this case, the Mac version (only for OS9) is very slowly and interface navigation is very different; this is due to intense use of contextual menus on the WIndows version, and Macs are provided with one button mices (to show the contextual menus you need to click+ctrl, and Mac users don't like so much to use contextual menus).
IMO, the programs that have the same use and functionality on different platforms (not only on Windows, Mac and Linux) are Mozilla/Netscape and Blender3D (this program will be redistributed again this month)

Yes, but Carlitus, I didn't mean software that have a Mac and a Windows version. What I mean is that all OSes should be able install the same program. The same installer file. Something I could install on my PC and that you could install on your Mac just the same. That way, all the softaware made for any plateform would be available for all.

paxx: In order for that to happen, the OSs in question would have to share patented structure and code openly, or build a standard, black-box translation layer on top of what is already there, adding complexity and subtracting performance. Even then, the visual interface for the 'translator' would have to be a whole new beast, since the varied OS interfaces are all patented as well. You'd end up with a generic UI running over any number of differently functioning operating systems, which could be a nightmare if you think about it.

Anyway, no one is gonna share that much code, or provide a free-use alternative to the patented visual interface they have fought so hard to promote...

Yeah, but it seems to me that if WINE can almost achieve that already, it might be possible. But I understand it's just a dream.

I dunno about much WINE, jsut that it kind of sits between the OS and the app, translating. I dunno how they make that work without stepping on MS's IP. I know that it is pretty touch-and-go, though, and with only one OS. It won't run Photoshop 7, anyway. (or I'd be talking to you from a linux box...)

paxx, that you are saying it's a utopia:
Mac & Windows are comercial OSes, that means indepndence for other platforms to be the most used (and purchased OS around). Linux too, gNome and KDE don't are using the same APIS, And BE, and Irix.
And there's the binary compatibility: x86, Itanium, PowerPC, etc. and special processing units (SSE, 3DNow, Altivec).
For this objective, there's the scripting languages, that are working very well on web sites (like Wincustomize) on any computer with a actual web browser.

This idea will be very good, but developpers are not according. There's also the same question for Customization Developpers: Stardock have their different concepts about Lighttek or mss styles. Windows, OSX and KDE-gNome are using the same graphics sources (32 bits colours graphics with alphablends) but are using different kind of files (in my opinion the best option is the gnome/kde, that uses a simple png file).