^^ smart 
TBH I would not recommend glass, because if you want it the same shape as the standard 900 window then that will be a right nightmare to get it cut and of course the fact that it can be very easy to break
See if you can remove the Perspex and get a company to cut you a new piece to the same shape as the old one, that you’re best bet,
And I was thinking of getting like a different colour Perspex window cut out for mine but I am not too sure on it

TBH I would not recommend glass, because if you want it the same shape as the standard 900 window then that will be a right nightmare to get it cut and of course the fact that it can be very easy to break
See if you can remove the Perspex and get a company to cut you a new piece to the same shape as the old one, that you’re best bet,
And I was thinking of getting like a different colour Perspex window cut out for mine but I am not too sure on it