Arlen H. Holder wrote:
On Wed, 19 Sep 2018 09:35:53 -0400, Wolf K wrote:

Possibly ordering by date created/modified. See waht you get when you
use command line DIR.

That's a good point that we should look to see the DOS order.
http://www.bild.me/bild.php?file=4441161testofdos.jpg

C:\tmp\faststonedir
Volume in drive C has no label.
Volume Serial Number is xxxxxxx

Directory of C:\tmp\faststone

09/18/2018 11:19 PM DIR .
09/18/2018 11:19 PM DIR ..
09/18/2018 11:26 PM 121,028 numbertest00.jpg
09/18/2018 07:03 PM 225,585 numbertest01.jpg
09/18/2018 07:05 PM 236,357 numbertest02.jpg
09/18/2018 07:05 PM 265,838 numbertest03.jpg
09/18/2018 07:07 PM 263,806 numbertest04.jpg
09/18/2018 07:17 PM 538,486 numbertest05.jpg
6 File(s) 1,651,100 bytes
2 Dir(s) 767,639,662,592 bytes free

Loading them, en massem into Paint 3D, I get 6 windows:
- bottom window = 00
- next window = 01
- next window = 05
- penultimate window = 02
- top window = 03
Testing a second time, I get a *different* order!
- bottom = 00
- next = 01
- next = 02
- next = 05
- next = 04
- top = 03

Running that through Paint.NET, I get:
- 00
- 02
- 03
- 05
- 01
- 04

Running that a second time through Paint.NET, I get:
- 00
- 03
- 04
- 05
- 01
- 02

One caveat I realized is that it _might_ matter which file we decide to
right click on to open all selected files. And Paul mentioned Windows
Defender, which I think is running on my system (but no AV is running).

I got something for you to try:

1) Start a trace running on Sysinternals Process Monitor.
(I was using this on a lark, hoping to see stupid
stuff being done out of order.)
2) For some reason, copies of notepad are opening
my set of four test files in alphabetical order
(in terms of windows opening on the screen). Whereas
when Process Monitor wasn't running, my four windows
were opening in random order.

For some reason, things are "a bit serialized".

I won't believe this is happening, unless
someone else reproduces it!

1) Create four text files: able.txt baker.txt cat.txt dog.txt
2) Highlight all four in File Explorer.
3) Select Edit from the right-click menu, which
causes four copies of Notepad to open.
4) When Process Monitor is running a trace, the
windows stack on the screen in the proper order.

Paul