Daniel van Vugt authored Aug 31, 2018 and Marco Trevisan committed Jun 07, 2019

When a user moves their cursor the perceived behaviour is that it will
pick what is under the cursor. However this isn't how picking works.
Picking does a virtual redraw of the screen, so in some cases what gets
picked isn't the same as what the user could see on the previous frame.
It more represents what will be drawn on the next frame than what is on
screen at present.

It may be unsafe to change these semantics, and they are useful anyway.
Just document it better.

!214