I use Ubuntu (64 bit). I saw some discussions about Ctrl+Space, but in my case I can’t do Ctrl+S, Ctrl+V, Ctrl+Z, Ctrl+Shift+F and, probably, something else (all these cases work fine in other programs, so it’s not a keyboard problem). It doesn’t work, then it does, then it doesn’t again. Is there a way to fix that? Thanks in advance.
I am also using 64-bit Ubuntu (12.04 now, 11.10 before that) and Eclipse. I was having similar problems like what you are describing, until I realized that keyboard input method/layout settings actually matter in Ubuntu (while it does not in Mac OS or Windows) while using copy/paste. If you are using two keyboard layouts (e.g. I am using English and Bulgarian), Ctrl–C / Ctrl–V will not work with the non-English layout. If it does no work, double-check the current keyboard layout.
It took me awhile to figure that out – hope it would help you too.
I’ve solved the same problem rebuilding my workspace CTRL + B on Windows
Looks like there are some key combination which screw up with the focus in the eclipse editor. Try using the shortcut for Focus Return