Shortcut for Full Screen Timeline

Is there a shortcut to enable and disable the Full Sreen Timeline Mode in the Workspace?

Not sure what you mean by "full screen timeline." There's a full screen GUI mode, available in the Workspace menu (but no keyboard shortcut that I'm aware of). In the Edit panel you can toggle between a full-column or half-column view of the media pool by clicking on the icon just to the left of the Media Pool icon in the top left. If you use the half-column view, it gives you a longer view of the timeline. But I suspect you're just after a keyboard shortcut to toggle between full-screen GUI view. There isn't one that I know of, you have to use the menu.

There isn't a default key binding for Full Screen Timeline, but it's not much of a bother to simply assign a custom binding in User Preferences (Keyboard Mapping).

@Reynaud Venter:

Yeah, that's it! I found the function in the preferences menue - and now it works!
The solution for me (german keyboard):
I press "#" to enable the Fullscreen Timeline, and to disable I press "#" again.

Thank you very much for this great tip!