Backgrounds for multiple desktops in KDE 4
 

I finally gave in and made the switch from KDE3 to KDE4, forced there by the gradually disappearing support for KDE3. One of my frustrations is that there doesn't seem to be any way to have different backgrounds for different desktops. In KDE3 it was straightforward to assign a different-colored background to each desktop. In KDE4 I can't see how to do it at all. (I'm running Kubuntu Karmic.)

This is annoying as the ability to recognise which desktop you are on was certainly a usability feature of kde.

Well, there is a way, but, as it is a relatively recent kde 4 feature and I'm not sure whether your kde is up-to-date enough.

I think that you have ~kde 4.3.0 (or maybe a bit later). By kde 4.3.3 or 4.3.4 the feature certainly existed, but I not sure exactly when it came in, so you might have it. Or, conceivably, not.

In any case, setting it isn't as straightforward/apparent as it was under kde 3.x. Select a desktop (say, desktop 1...btw, this is inaccurate as the things that look like desktops are really 'activities' now, whatever difference that makes), go to the desktop config (right click on the wallpaper, select desktop configuration) and change the wallpaper for that desktop (err, activity). Select another desktop and change the wallpaper for that.

If they change independently, you have the feature, but if they stay in sync, you don't.

Versions
 

I'm running KDE 4.3.2, which I got off a Kubuntu distribution CD and have been updating assiduously. And the desktops do change in sync: a change in one affects all the others in the same way.

This regression of function is one of my pet peeves about KDE4, although I guess it will eventually be remedied. The other one (I know this is off-topic) is the fact that spellchecking can't be disabled, only reconfigured.

Any advice about what version of KDE4 I should be running and how to integrate it into Kubuntu?

The feature worked for me in KDE 4.1 (gentoo), but my second monitor broke so I can't tell now.

The latest.

Can't help you with the kubuntu part, but I assume that its just a matter of selecting it in synaptic. Well, once you have got the appropriate repos enabled, and that's the part that I can't help you with, but I assume that there is some kind of 'how to' available.

Oh, and once you have a version where every significant bit works, don't update it monthly any more, otherwise you'll break stuff that had originally been working.