Ok thx marc and the goal is actually to make some small additions to the IslandRTL itself, if carlo decides these are worthy to add, but since I saw that you guys have already something similar there (but for Island this is not the most performant way of doing it) I decided to change that 
Ok im really close to have it work, but the only build error now I get is this, which im wondering now why:
Its only this variant type which seems to be used multiple times, but not sure why, actually.
So the basic structure of that “island.sln” is now:
- island.sln
- ConsoleTestApp
- Island.Windows.Elements (references the exact Island.shared below)
- Island.Shared
Forget about that issue also… I solved it, since I had still a double “island.fx” reference AND the island.shared referenced so this cant work… my appolog
Look at the full text of the error messages that are so convenient;y cut off in your screenshot.
And you look again on the comment above you 
I already fixed it mate, but thx still haha