Wrong screen information shown in customer tool

[pinhead84]

If multiple monitors are used on Linux systems, the customer tool shows wrong screen information in the screen selection field. The resolution of monitor A is shown, if monitor B is selected. The user might select the wrong screen because of the wrong / misleading information.

I'm not sure, if this happens in any case and for all operating systems - but GraphicsDevice#getDisplayMode() undoubtably returns wrong values in certain situations. Therefore we're not calling this method in the future and extract screen information via GraphicsDevice#getDefaultConfiguration() instead, which returns the expected values.