Hi
If you click the OK Button, and the IDE stays there; try rebuilding the IDE from the Tools Menu, this has sometimes fixed an odd Startup with Laz-FPC-Trunk->for Cocoa.
Please always check that you are using the very latest Trunk version when testing Laz(1.9.0) Cocoa, as it is being rapidly developed multi comit changes per day in some cases; and it is probable that a fix/addition may have a knock on effect, if so report to forum to check if others can confirm and then post on bugtracker, this is the best route to getting Lazarus-Cocoa working...