I have both - LisaEm has been invaluable, and I also have a Lisa I can refer to in cases where LisaEm isn't perfect.
It's not 100% faithful - I describe some of the differences here: https://lisagui.com/info.html For the features I've added or changed, I tried to use the same UI conventions and principles found in the Lisa Office System (or early versions of Mac OS if LOS has no precedent).
It's not so much that it's "hard" as it was time consuming to write so much of it from scratch.
I have both - LisaEm has been invaluable, and I also have a Lisa I can refer to in cases where LisaEm isn't perfect.
It's not 100% faithful - I describe some of the differences here: https://lisagui.com/info.html For the features I've added or changed, I tried to use the same UI conventions and principles found in the Lisa Office System (or early versions of Mac OS if LOS has no precedent).
It's not so much that it's "hard" as it was time consuming to write so much of it from scratch.