Quick Look: How to return to unindexed view using mouse
After selecting some images and pressing ≪Spacebar≫, I click on the index button: 
This is what I see:
Without the keyboard (Ctrl-Enter), how do I get back to the unindexed view?
Solution 1:
On 10.13.2 a single click on any image returns to Quick Look on just that image, as hover on any image highlights with a blue rectangle.
Solution 2:
Testing it on 10.13 it seems you have to double click on the image you want to return to the full size preview of.