Hi Thijs, > Mind that coroutine.running () changed from 5.1 to 5.2. Good point; from the manual ( http://www.lua.org/manual/5.2/manual.html#pdf-coroutine.running): ...Returns the running coroutine plus a boolean, true when the running coroutine is the main one. I need to take that into account in Mobdebug as there are couple of places that can be affected by this change (only running under 5.2 or LuaJIT with LUAJIT_ENABLE_LUA52COMPAT). Paul.