I have 2 projects, A and B
project B have in his build path > libraries the class folder of A (eclipse also recognized that there is a "Source attachment" and added it.
Both A and B are in the same workspace.
When I ctrl+click into a function of project A referenced into a file of B eclipse open the
You can use Ctrl+Shift+T to open a search Dialog.
But you should add B as a dependent project of A (and remove it from the classpath).