Yeah, as I think of it, a change has occurred is when the output of a succeeding rendering is not similar to the previous..
Here is a simple boiled down version of the problem:
function prepare()
v = math.random()
end;
function get_sample(x, y)
return v,v,v,1
end;
This will produce different output each time it is rendered, but the current FF mechanism for changed status will not catch this.
Now I consider such a construction wrong, because I should have added a
math.randomseed(VARIATION) to the start of prepare..
But that is exactly the point: how will I know this is wrong when FF don't rerender the output? The current behaviour of "Apply Changes" leads me into a false conclusion that the output is consistent..
(you need to change the script with linebreaks or similar to force changed status)