If you have the smoked double bubble ZG screen, you can take some rough steel woool to take off the shiny finish on the side of the screen facing the dashboard. This will rough up the surface just enough to prevent the sunlight from focusing and melting your dash plastic. Since the screen is smoked and kind of opaque anyways, no one but you will know that the inside of the screen isn't shiny anymore. Not sure how noticeable this would be on an amber screen since its more translucent. Probably just a very mild "frosted" look.
My dash got some sunlight scorching when I first put the DB screen on, but haven't had any more problems after taking the shine off the inside of the screen.
FYI- the problem happens when the tail of the bike is pointed at the sun. The screen acts as a parabolic reflector, focusing sunlight on the top lip of the instrument cluster. I contacted Zero Gravity about this years ago after my experience and they acknowledged the problem but didn't seem too interested in fixing it. It also happens with their DB screens on other sportbikes according to the technical rep I spoke with.
It's a no-cost and virtually unnoticeable fix if you like the look of the smoked ZG DB screen but were previously scared off from getting one because of the dash-melting reports.