My point is very straightforward, maybe even eccentric in some people's opinion - I would just like easily to be able to distinguish the image I have selected, period, without having to squint at the filmstrip to make sure. That's all.
The control c/v etc method is a good tip for those who don't know about it.
However, in your example 2, where all the images are already selected, it's not quite as easy as you suggest to readily see the source image - at least to my ageing eyes. Where an image is going to be the source of across-the board significant changes to many images, that bestows a very important status on the source image and as such it should stick out like a sore thumb as a matter of good working practice.: A change of border colour or something like that would be nice. As things stand, the difference between a selected image and a source image in terms of differentiation is definitely not striking enough by any standards. Simple as that.
Cheers
Incidentally, because I hadn't done so before, I tried your methods as outlined above - and they didn't work for me.
Interesting.
I usually use the copy/paste buttons on at the bottom of left panel in Develop mode or the sync facility. Since reading your tips above, I've tried several times and still can't get it to work.