Method to determine if a delegate is registered
Point in Polygon method
Game Objects store data about visibility in current viewport

With corresponding getter and setter methods.
Store viewports in an array
Draw viewports in the order they were added
Add invert method to matrix-3x3.js
Add matrix-3x3.js as a dependency
Store name in the viewport
Store matrix of viewport
Property and method to enable or disable mouse events on a viewport
Method to tell if a point is inside a viewport

Absolute canvas coordinates
Store the visibility state of a game object for a given viewport
Missing spaces
Convert Canvas coordinates to viewport coordinates