The Screen object has information about the subject screen, such as screen size, refresh rate, etc.
Screen.SubjectScreenRect % [left top right bottom] in Windows coordinates
Screen.Xsize % in pixels
Screen.Ysize % in pixels
Screen.SubjectScreenAspectRatio % Xsize / Ysize
Screen.SubjectScreenFullSize % [Xsize Ysize]
Screen.SubjectScreenHalfSize % 0.5 * [Xsize Ysize]
Screen.RefreshRate % in hertz
Screen.FrameLength % in milliseconds
Screen.BackgroundColor % [R G B]
Screen.PixelsPerDegree % a positive scalar
It is accessible in the timing file. Even when it is not directly available, you can retrieve it from MLConfig.
Screen = MLConfig.Screen;
In adapters of the scene framework, access it via the tracker object.
Screen = obj.Tracker.Screen; % in adapters