Ah, that makes sense.
The problem with putting a zoom function in an app like that is that it doesn't really make sense without a a pan function and that doesn't really make sense without an infinite field.
It is something I'd like to add to it but it becomes a whole different thing to add that.
As it is the field is basically a fixed size 2D array. To change that means making it a single array (changing size) with pointers between the cells and their neighbours. Deleting any that don't have alive neighbours adding cells that had no neighbours but get some on the next gen, etc...
Even once you have that you then need some sort of infinite coord system that somehow clears itself if the field becomes empty.
Then, how can you randomise the grid? It would have to be randomised over a certain area rather than the whole area.
I've thought about it before but never actually tried to do it.