Additional QoL level editor features

[ThePizzaEater1000]

I've already brought up some of these features in my own level editor suggestion thread, but nonetheless, I don't object to any of these - these are all excellent decisions.
The woes of filling in a too-big canvas can just be alleviated if block fill had a maximum fill area (maybe to the zoom of your current screen).

You could also allow large fills, but have an "Are you sure?" popup that says that there may be lag or even a crash if the fill area exceeds, say, 50000 blocks. (though probably higher than this, since block placement doesn't cause much lag, and I've done larger fills before)