Why doesn't the key to switch on all scene layers work on linux Since I use Blender (2.12), the key on a german keyboard on windows to switch on all layers is Ö (right to the L).

In Ubuntu it doesn't work and never has for me and I'm using Linux for at least 6 years now.

Is there any reason behind that? After some research it seems as if Blender didn't recognize a lot of special keys (mostly keys between the letter keys and return) for keyboard shortcuts while it easily manages to do so for typing text. They don't work in the game engine's keyboard sensors as well. I can't imagine this to be a bug since it's been like that forever. Is there a setting I miss?

Here's a list of keys that Blender does recognize when typing text and completely ignores for shortcuts:
Everything horizontally between 

L and Return, 

P and Return, 

0 and Back Space,

the key to the left of Y

as well as the key to the left of 1
Is your keymapping set correctly in your Ubuntu conifg? On a QWERTY keyboard, the default for enabling all layers is backtick (`... it's the top-left key, to the left of 1). Does that work for you?