Version: (using KDE 4.3.2) OS: Linux Installed from: Ubuntu Packages It's not possible to use any global shortcuts while in the desktop-grid or present-windows effect. That means its not possible to adjust the volume or start/stop music via global shortcuts and multimedia keys.
Yes kwin does a global keyboard grab to ensure that all key events are passed to the effect. All kwin functionality does that: you can't use a global shortcut while using alt+tab or while resizing/moving a window. I'm not sure if that could be changed. We have to ensure that the effects aren't messed around. If we don't block global shortcuts, it would be possible to start alt+tab or present windows in desktop grid, which wouldn't work.
Couldn't you just check if another effect is already running? It's no so interesting to use global shortcuts while alt+tabbing through windows, but when in the desktop grid or in present windows it might make a lot of sense. Is it also kwin that grab the global shortcuts when I right-click something?
thinking again about it: no, it's a bad idea to enable global shortcuts in effects. E.g. you are in present windows and press alt+f2. The krunner would be opened (perhaps in normal size), the user would start typing and it would be the filter instead of the krunner interface. Those effects are modal and have to be modal and by that have to grab all keyevents. Sorry wontfix
*** Bug 328264 has been marked as a duplicate of this bug. ***