> You're missing the point. You're proposing we implement the capacity
> to provide a certain kind of GUI feature. Before we do that, I want
> to know whether users expect or want that kind of feature in GUIs. If
> they don't, let's save the trouble of writing and maintaining code to
> implement it.
Yes, click and drag and mouse-2, mouse-3 are used in UIs.
That is not the question.
The question is whether other UIs make a distinction of down and up
clicks on tool bars. And what UI design recommendations say about it.