OK. The clock demo runs. A console with some numbers. Looks fine.
If there are newbies who want this seup, to achieve this:
in Ubuntu package manager search "sfml" install all. (I didn't install debug-symbols though.)
Open C::B
In, Project Build Options > Linker Settings > Link Libraries >Add (sfml-system)
and in, Project Build Options > Compiler Settings > #Defines > Add (SFML_DYNAMIC)
Now I need to test some gfx.
Tutorial - Window - Handling events
Copying the .cpp into the previous project seems to work, when I add "sfml-window" and "sfml-graphigs".
However i'm running compiz and all i get is a window with garbage.