Cancellations are missing

[Findecanor]

These are really two issues:

1. On classic Mac if you held and dragged the scrollbar knob but moved too much in the orthogonal direction, you dropped the knob and it reverted to its original position before you clicked it.

I think Windows 3.0 also had the same behaviour as Mac.

I remember this as an annoyance, because I was used to the Amiga which didn't have this behaviour.
On Amiga you cancelled a drag by pressing the right mouse button.

(I'm not sure if newer Mac and Windows had this behaviour)

2. On older and newer Mac and Windows, NextStep and Amiga, if you click a button widget, the button is activated only as long as the mouse pointer is over the button.