A specialized jStage.UIActor that fades into view, lingers, fades out of view, then self-disposes.
The two speed parameters in the constructor can be thought of as being functions of full opacity over time; that is, if a value of 0.5 is passed, this means that 0.5, or half, of the object's full opacity, or 1.0, will be faded per second. Essentially, higher is faster, lower is slower.
base:Another Actor upon which to 'base' this one (in the scene graph). A properly implemented jStage game will use a jStage.Stage as the base of the scene graph, so this parameter should not be null or undefined.
width:The width, in pixels, of this UIPopupActor.
height:The width, in pixels, of this UIPopupActor.
fadeInSpeed:The speed at which the UIPopupActor fades into view.
lingerTime:The time, in seconds, that the actor lingers between fully fading in and beginning to fade out.
fadeOutSpeed:The speed at which the UIPopupActor fades out of view.