I had to move some layers around in a project to make room for another layer underneath and found that this messed up most of my code which referenced layers.
The code referenced my HUD on layer 3 but I had to move the HUD to layer 4, but all the code was still referencing level 3.
I've noticed how if you change the name of a variable it will automatically change the name everywhere else (which is fantastic) and I was thinking it would be a really useful to make it track which layer it is referencing in the same way