How to unfocus a NativeWindow for unit testing

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// At the moment, AIR only has activate() and bringToFront() for focusing windows,
// but it lacks any methods for unfocusing. Though unfocusing a window is a pretty
// rare action, it's necessary for some unit tests. Mine test a minimize menu item
// that is expected to be disabled if no windows are focused. I don't see the AIR
// team adding a deactivate() method, but I do see the possibility of setting
// NativeApplication.nativeApplication.activeWindow to null. Right now, it's read-only.

var window:NativeWindow = NativeApplication.nativeApplication.activeWindow;

window.visible = false;
window.visible = true;