hey ijoin, you would make a separate layout to function as your loading screen,
you can place whatever you like on this loading layout, anything from a progress bar or a simple timed transition
I do know that layout transitions are feature that are planned for upcoming releases , but its not hard to make a fade in blackout by using a new layer set at the top of other layers with a pure black sprite object (can be quite small say 128by 128 pixels that you apply a fade behavior to...fade in and out the blackout and call it anytime you like in your events screen with any set delay or timer you like.
loading progress bars are easy to make and dont really have to be accurate, you can just make a timed loading screen to pace out your gameplay flow
i find its a nice addition to any game to have little feature loading screens ..showcasing artwork or whatever you like in between levels
some useful links for you to read..