I think so, hence my opening sentence. I think it is also fair to say that library-writers generally have less leeway in this matter than application writers, w

I think so, hence my opening sentence. I think it is also fair to say that library-writers generally have less leeway in this matter than application writers, who may know that certain scenarios are not a problem. BTW, I have updated my original post to mention swapping source and destination, another common idiom for satisfying the requirement.