Well, that explains why it doesn't work.
I tried the "external dependencies": This only re-links the project when the depency changes, it doesnt re-compile the source. Furthermore, when building the dependant, it doesn't trigger compilation (when needed) of the dependency. Which seem logical, cause with "external depency" C::B doesn't know, the file (in this case the compiler-binary), origins from another project in the same workspace. So this isn't what I I would like to have. Thanks anyway.
For the time being, the problem isn't critical, as I have only two projects. Just was wondering, how the "project's depencies" work in C::B.
My C::B version is 10.05 (ubuntu repository).