The one thing that pisses me off with UNIX systems is how programs don't interoperate or communicate with each other very well and there's no standard way to have a default browser or mail client unlike Mac OS or Windows.
GNOME can do that, and I think KDE can too. "Desktop > Preferences > Preferred Applications" in GNOME.
Setting your default email and web clients to thunderbird and mozilla in KDE does nothing.
Definetly something wrong there.I can click on a link in GAIM and it opens in firefox. Changing the default browser to "blahblah" in GNOME's preferred applications causes an error when I click a link in GAIM. Clicking URLs in kspread launches Konqueror, as expected.
I'm unclear on what you meant here. Are you saying things work like they should for you, or they don't work like they should?
Things work like they were intended to. Applications will chose to ask GNOME or KDE or whatever or nothing for a browser or mail client or terminal to run.
Try setting firefox to your default brower and then clicking a link from an email in thunderbird or setting thunderbird as your default mail client and clicking a "mailto" link in firefox. Does it work then?
But If I set up KDE to use FireFox as the default html viewer the setting only affects KDE, Gnome, Xfce are all unaffected, hence there's no standard way to set a default application for a particular purpose, the same applies to drag and drop, DDE and OLE across on any UNIX platform, Windows and Mac OS are better in this respect.