public static function build(configClass:Class, viewRoot:DisplayObject = null):Context
	 Builds a Context from the specified MXML configuration class.
	 The returned Context instance may not be fully initialized if it requires asynchronous operations.
	 You can check its state with its configured and initialized properties.
	 
	 
 Parameters 
 | configClass:Class — the class that contains the MXML configuration
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 | viewRoot:DisplayObject (default = null) — the initial view root for dynamically wiring view objects
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Returns | Context — a new Context instance, possibly not fully initialized yet
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