You discovered a bug in the engine, and you are sure that it is not a problem of your code? Just post it in here. Please read the bug posting guidelines first.
Haven't been found a solution yet?
I use Irrlicht 1.6.1 on Mac OS 10.5.8. I builded the XCode project in source/ and using libIrrlicht.a. After running my application, it goes behind the current application and no keyboard input is able to be taken. All keyboard input goes to previous application. Also I cannot see the application with clicking, it stays at back of the previous application. Only if I have a smaller sized window in front of my application, I am able to see it.