@mouser: Well it happened first in SC (v4.12.0) whilst using a Samsung-S3 laptop, and I (erroneously, as it turned out) put it down to probably being the Samsung's keyboard, which seems to have a problem that needs fixing at the BIOS level (the function keys, and function lock do not work properly). I guessed that the keyboard control processor or mouse could be outputting garbled instructions, or something.
However, yesterday I was using SC (v4.12.0) on a ToshibaL855D laptop and was surprised to see the exact same error. Now I
think that by that stage, all the Win10 and MS Office auto-updates had completed, and it was
then that I updated SC to v4.13.0. Testing after that showed to my pleasant surprise that the error seemed to have gone away.
So, though I feel reasonably sure from the foregoing that the SC v4.13.0 update
probably fixed it, I can't be certain.
I did think of doing exactly what you suggest - namely, "...install 4.12 on top of 4.13 temporarily and see if the problem is still there. ...", but, as you suggest, it is a new/uncommon issue, and since it's "gone away", I'd be unwilling to invest any more of my time in it unless I had to for some reason. It'd be of academic value at best.
You ask me "you do know that SC has a very easy built-in ability to combine images side-by-side (vertically, horizontally, with various automatic resizing options)?". Yes, I do know that, and I have occasionally used that functionality and its overlaying capability when I have needed it, but for me the issue tends to be "what's the quickest or most efficient way of getting the image manipulation done effectively?", and since a lot of the image capture tends to be via OneNote's
Send to OneNote clipping tool, and imprecise clips are fine, then it is easiest to do it all in OneNote, wrapped up amongst the text in some notes, and completed there. The quality of the result is usually pretty impressive.
However, OneNote's image manipulation and drawing tools are mediocre at best, its overlaying is a joke and doesn't work, and so I rarely, if ever use OneNote for those things. Instead, to get the job done quickly, efficiently and effectively I then always use SC. In fact, it was whilst I was coaching my daughter on the use of SC for some work on a school project that I observed the error on her Samsung-S3 laptop. I'd told her how great SC was and how it made light work of the heavy lifting of image manipulation, and there it didn't work!
I was wanting to get to the bottom of it, and I was using the Toshiba as that was a known quantity. It's a virtual no-brainer to always use SC, because that is usually rock solid and reliable.
Looking ahead, it would be great if I could use SC in place of
Send to OneNote, as a more efficient input front end to OneNote and as an efficient input front end to ABBYY Screenshot Reader. It would be even better if SC was also integrated with CHS and/or the MS OCR API - as I think I have separately suggested for CHS. ...