I use macbook pro and my system is OS X 10.10.3. And I have a external monitor. My SDK version is 18.0.
Use the following code:
nativeWindow = new NativeWindow(new NativeWindowInitOptions());
When starting the project the windows appeared in my macbook's monitor. After the 'nativeWindow' closed, I close my macbook's lid. And then the Air application crashed when it adjusting it's position to the external monitor.
I guess there is some list keep the nativeWindow in air. And it doesn't remove the closed window.