NimPlugin: Wrong display inside Navigator on macOS

Steps to reproduce:

• ensure to have NimPlugin enabled, create Nim Application with the wizard

Current result:

• project gets created, but is displayed wrong inside Navigator (depending on whether there are other opened projects it just shows one of the projects nodes (or itself if no other projects are opened) as sub items)
• the sub node feels - more or less - like no sub node at all (if clicked, the node and the project node get selected - depending on whether the project node of another project has been used this could be even mark another project)

Note: On Linux I'm getting correctly the main.nim file displayed as sub item. (but I'm getting several soft-asserts - will raise another bug report for this)