Use case:

Bob is a developper on public project A and he wants to move an Issue to public project B. He's a Developper on project A with all the "Issue tracking" permissions enabled, including "Move issues". He's a Non member on project B and the Non members also have all the "Issue tracking" permissions enabled, including "Move issues".

According to permissions, he should be able to move an Issue from project A to project B but he can't, in Redmine v0.9.3 anyway. So that's a bug IMHO.

The workaround is to give Bob the role "Rapporteur" in project B (in French, not sure about the term in the English version). "Rapporteur" also has all the "Issue tracking" permissions enabled. In that scenario, Bob can indeed move an Issue from project A to B.

That's inconvenient though because we need to give everyone the "Rapporteur" role in every single project.