Given two projects (A and B) which share the same sources, but have different configurations.

Opened project A and did some work.
Closed A, opened B.
No editors open yet in B.
Opened a class using 'Go to Type'.
Used 'Select in Projects'.

Now netbeans wants to open project A instead of selecting the file in 
project B where i opened if from (at least I think that this is what I did).

I would expect that netbeans only works with currently opened projects if I use 'Go to Type' or 'Select in Projects' (at least primarily).

After closing the project all editors remain open as if netbeans lost the connection between opened files and the project they were opened from.

Filesystem structure of (all) my projects:

basedir
+ bin
+ dist
+ nb_project_A
  + nbproject
+ nb_project_B
  + nbproject
+ src
+ test

BTW:
If there is not any open project, there is no way to use 'Go to Type', 
so why have the opened files been associated to a different project?

If I open a completely different project I'm not able to use 'Go to Type' to navigate to any 'outside source' (e.g. a source of project A or B), and that is expectance compliant.