The class should extend something , try extends TStaticVar.
It will probably make it singleton but eh as long as you only use it once.
But also GS1-3 not being a proper language, it doesn't act like proper languages.
Oddly playing around, if you create the object, the class can extend it o.0 not the actual class though?
PHP Code:
//#GS3
class Foot extends TStaticVar{
var id:int;
}
class Toe extends Foot{
var id:int;
}
function onCreated():void{
var Foot:Foot = new Foot();
var toe : Toe = new Toe();
toe.id = 1;
echo(toe.id);
}