i am getting this error when i apply your code.
ArgumentError: Error #2025: The supplied DisplayObject must be a child of the
caller.
at flash.display::DisplayObjectContainer/removeChild()
at mx.core::Container/removeChild()
at custom_comps::login_register/closeWindow()
at custom_comps::login_register/___TitleWindow1_close()
at flash.events::EventDispatcher/dispatchEventFunction()
at flash.events::EventDispatcher/dispatchEvent()
at mx.core::UIComponent/dispatchEvent()
at mx.containers::Panel/closeButton_clickHandler()