Xfce & KDE Change Each Others Settings.
 

I've been able to confirm that Xfce 4.8 and KDE 4.8 (and earlier) can, and do, change each others settings.

Take for example, three things I've seen it do. If you, in Xfce, via the auto start applications, setup a audio file to play on start up, the blueman applet (or manager) to appear in the panel on startup, and the wicd applet, also to appear in the panel on startup, these same things will appear in the KDE settings under, "System Settings, Startup and Shutdown, Autostart."

If you delete one or all of them from KDE, they will be deleted from Xfce and vice versa. If you remove the check mark next to any of the programs you setup in Xfce, the check mark will be removed from the same entry appearing in the KDE, Startup and Shutdown, Autostart settings.

This must, but I really don't know, have something to do with how KDE can, and does, scramble the windows manager and mouse settings in Xfce 4.8 (but not 4.6.2).

BTW. When you switch to KDE after setting up the start up audio file in Xfce, even after a re-boot, you can hear that music file playing in the background in KDE at the same time as the start up audio you picked for KDE.

That's because both are using xdg-utils, a brief quote:
That's from http://linuxappfinder.com/package/xdg-utils, other info about Portland at the product page, http://portland.freedesktop.org/wiki/

I find part of xdg-utils handy; when using 'open' instead of 'save' for a firefox download I use '/usr/bin/xdg-open' as the file handler. Most file types simply Do The Right Thing[TM].

OK. Then is there anyway to stop them from sharing the information or is this their way of forcing a user to stick to one particular DE?

Actually, I was a little too detailed above. KDE and XFCE both are both implementing the standards from freedesktop.org, if I understand correctly. Part of that is Portland, but the whole idea is to share configuration information. KDE has done it longer, and XFCE is moving in that direction. This movement on the part of XFCE is what is driving the 'bloat' of XFCE about which some people are complaining.

Regarding your question about making them stop sharing information: Sure, you _could_ make some complicated scripts that wrap the startup of KDE and XFCE and copy/rename specific saved-off copies of different configurations for both environments _into_ the freedesktop standard names. Complicated, messy, and you'd have to keep updating both as new versions of KDE and XFCE came out. Not worth it in the long run, IMHO.

About the other question, limiting a user to a single DE. It doesn't limit them to just one. Simply, as the software matures, your DEs will act in a more uniform manner. Configs doing the same thing in multiple environments is the target. Some oddities along the way will be found, and later fixed (IMO), but there really isn't any forcing to one DE going on that I can see.

In the long run, the software is going in the direction chosen by the developers. Petition them for options you'd like, learn to like what they like, or choose different software. If enough people feel as you perhaps someone will fork it.

good luck! :)

Thanks for the information. Greatly appreciated.
Can't say I like the way things are headed in regard to this problem. Xfce, especially, seems to be going off in the wrong direction. KDE has been a write off since the release of 4.0.