Not working I'm afraid, here's the sequence of events:
- boot Mageia, open Firefox. Desktop 1 button on taskbar is lit up by default, Firefox appears in the button (and obviously on the screen).
- click the desktop 2 button on taskbar. Desktop 2 button is now lit up, Firefox still on screen.
- fire up Chromium. Firefox and Chromium are now both onscreen and both visible in the desktop 1 button on the taskbar (not lit).
- click the desktop 1 button. Desktop 1 is lit up again, nothing changes on screen - still both browsers.
This isn't a huge deal to me personally because I don't use multiple desktops anyway (just wanted to play with the cool 3D desktop cube effect

effects don't work anyway!). I really just wanted to know if it's a bug with Mageia or just my installation being awkward. I've installed the radeon-firmware package by the way, don't know if that would affect it. Other than that it's only Chromium I've installed.
Other potential buggy thing is the start menu (or whatever you call it, Kickoff replacement), submenus of it don't always appear properly, I just get the left sliver of them that overlaps the main menu. Rolling up and down them for a second or two usually gets them opening properly. Again, not a big deal, just wondering if it's an issue. And again I'm not sure if it was there before I installed the Radeon drivers (might have been but they were the first thing I installed). Other than these things though and no KDE special effects, I'm pretty impressed with Mageia!