Size of content on the stage:

stage.width + stage.height.

The dimensions of the monitor that the flash player currently is consuming:

stage.stageWidth + stage.stageHeight.

Dimensions of the swf in the Fla’s publish settings:

loaderInfo.width + loaderInfo.height.

Access to main stage ( formerly know as _root in as2 ):

var swfStage:Stage = anyDisplayObject.stage.

private, protected, internal and public

If a property is declared with the public keyword, the property is visible to code anywhere. This means that the public keyword, unlike the private, protected, and internal keywords, places no restrictions on property inheritance.

If a property is declared with private keyword, it is visible only in the class that defines it, which means that it is not inherited by any subclasses. This behavior is different from previous versions of ActionScript, where the private keyword behaved more like the ActionScript 3.0 protected keyword.

The protected keyword indicates that a property is visible not only within the class that defines it, but also to all subclasses. Unlike the protected keyword in the Java programming language, the protected keyword in ActionScript 3.0 does not make a property visible to all other classes in the same package. In ActionScript 3.0, only subclasses can access a property declared with the protected keyword. Moreover, a protected property is visible to a subclass whether the subclass is in the same package as the base class or in a different package.

To limit the visibility of a property to the package in which it is defined, use the internal keyword or do not use any access control specifier. The internal access control specifier is the default access control specifier that applies when one is not specified. A property marked as internal will be inherited only by a subclass that resides in the same package.