@box said:
By Solid selection fence I mean the difference between selecting from left to right and right to left.
Have a look at this gif and notice the dotted selection fence and the solid selection fence and what they select. Left to right creates a solid framed box which selects everything entirely within that box. Right to left is a dotted line box that selects everything it touches.
So in the earlier selection I when left to right and stayed above the back edge line so it selected the whole top.I'm afraid it's not off to bed yet, there is pub time to deal with.
In all the time playing with SU I've never realised the selection 'fence' does that! 😳 Very useful to know thanks.