Lists components under a specific point in global, screen coordinates.
Note: this function will return *every single* components at a specific point,
even if they have no backgrounds, or haven't got anything drawn onto them.
Parameters
screenX:Float  | The global, on-screen x position of the point to check for components under | 
screenY:Float  | The global, on-screen y position of the point to check for components under | 
type:Class<T> = null  | Used to filter all components that aren't of a specific type. null by default, which means no filter is applied. | 
Returns
| An array of all components that overlap the "global" position (x, y) |