Can I still create Global variables in AS3 - actionscript-3

Question

Following the answer here, I have created a file called MyGlobals.as and placed some global variables and functions so that I can access it from anywhere within my project just like AS3 buil-in functions such as trace() method.
This is MyGlobals.as which is located in the src folder (top level folder)
package {
public var MessageQueue:Array = new Array();
public var main:Main;
public var BOOKING_STATUS_DATA:Object;
public function postMessage(msg:Object):void {
MessageQueue.push(msg);
}
public function processMessage():void {
var msg:Object = MessageQueue.pop();
if (msg) {
switch (msg.type) {
}
}
}
Looks like my IDE (FD4) is also recognizing all these functions and variables and also highlighting the varibles and functions just like any other built-in global functions. However, I am getting compilation errors "Accessing possibly undefined variable xxx". The code is as simple as trace(MessageQueue) inside my Main (or another classe).
I am wondering if there was any change Adboe has done recently that it can't be done now or am I missing something? I am not sure if I need to give any special instructions to FD to include this MyGlobals.as?
I am using FD4, Flex SKD 3.1, FP12.0
I am aware of the best practices which suggests to avoid using this type of method for creating global variables but I really need it for my project for my comfort which I feel best way (right now) when compared to take any other path which involves daunting task of code refactoring. I just want do something which can be done in AS3 which I guess is not a hack.

Answer 1

I've done some playing around; it looks like you can only define one (1) property or method at package level per .as file. It must be the same name (case-sensitive) as the .as file it is contained in.
So no, nothing has changed since the older Flash Versions.
In your case that would mean you need five separate ActionScript files along the lines of:
MessageQueue.as:
package
{
public var MessageQueue:Array;
}
main.as:
package
{
public var main:Main;
}
...etc. As you can see this is very cumbersome, another downside to the many others when using this approach. I suggest using the singleton pattern in this scenario instead.

Answer 2

package{
public class Singleton{
private static var _instance:Singleton=null;
private var _score:Number=0;
public function Singleton(e:SingletonEnforcer){
trace(‘new instance of singleton created’);
}
public static function getInstance():Singleton{
if(_instance==null){
_instance=new Singleton(new SingletonEnforcer());
}
return _instance;
}
public function get score():Number{
return _score;
}
public function set score(newScore:Number):void{
_score=newScore;
}
}
}
then iin your any as3 class if you import the singleton class
import Singleton
thn where u need to update the global var_score
use for example
var s:Singleton=Singleton.getInstance();
s.score=50;
trace(s.score);
same thing to display the 50 from another class
var wawa:Singleton=Singleton.getInstance();
trace(wawa.score)