I've posted to the AIR forum but I'm beginning to think this is a Flex framework question. This sounds like the issue (https://issues.apache.org/jira/browse/FLEX-17097) but I've hit a deadend trying to debug this thing.
I'm working on an app and I'm pretty stuck as the only code that comes up is below. I am trapping the escape key to stop a process. There are no Alerts in the message chain and I'm not quite sure where to go with the information I'm given, which occurs when I press the escape key.
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at mx.accessibility::AlertAccImpl/eventHandler()[E:\dev\4.y\frameworks\projects\mx\src\mx\ac cessibility\AlertAccImpl.as:177]
at mx.core::UIComponent/dispatchEvent()[E:\dev\4.y\frameworks\projects\framework\src\mx\core \UIComponent.as:13152]
at mx.controls.alertClasses::AlertForm/removeAlert()[E:\dev\4.y\frameworks\projects\mx\src\m x\controls\alertClasses\AlertForm.as:522]
at mx.controls.alertClasses::AlertForm/keyDownHandler()[E:\dev\4.y\frameworks\projects\mx\sr c\mx\controls\alertClasses\AlertForm.as:546]
The framework code that it errors out at is the following. It says that systemManager is null. How can one make system manager null?
override protected function eventHandler(event:Event):void
// Let AccImpl class handle the events
// that all accessible UIComponents understand.
const systemManager:ISystemManager = ISystemManager(master.parent);
titleBar = Alert(master).getTitleBar();
There's an Alert somewhere. Could be in a library. Put a breakpoint on the Alert.show() and see who calls it.
SystemManager might be null when an object is removed from the display list.
Apache Flex has made some attempts to fix a similar error, but I'm not sure if it will fix your situation. If you can come up with a simple test case, post it.