CUA mode is implictly cutting and copying from region

Question

I'm confused about some CUA mode implicit behaviour that I got after upgrading Emacs, specifically:

• Marking a region automatically copies it, without having to type C-c
• Deleting a region automatically kills it, without having to type C-x

I find this confusing because I often want to kill a region with C-x, do a backspace on a second region to delete it and then paste with C-v to replace with the original region.

I find however that once I delete the second region, it replaces the first one in the kill ring and I get it pasted right back again after C-v.

EDIT: Here's an example of what is currently happening. Suppose I have a buffer with these two lines

This number is 1
This number is 2

I want to swap the characters 1 and 2 between the two lines. I try to take these steps:

Put a region around '1' and cut it with C-x. The character duly disappears:

This number is 
This number is 2

Put a region around '2' and type backspace to delete:

This number is
This number is

Put the cursor at the end of the second line and type C-v in the hope that it will paste the '1' character. What I get instead is:

This number is
This number is 2

So, deleting the region around '2' implicitly put it in the kill ring, as if I had typed C-x.

A similar thing happens just by setting the region, which CUA is implicitly copying as if I had typed C-c. If I then move the cursor somewhere else and type C-v, I get the region pasted back.

Is this normal behaviour? I would prefer to do the cutting and copying explicitly, without CUA doing it behind my back.

Answer 1

I found the culprit. I had this customisation in my .emacs that I had forgotten about:

(select-enable-primary t)

I don't understand how this would interfere with CUA but I removed this customisation without any observable adverse effects so far.

Answer 2

I do not see what you report, when starting Emacs using emacs -Q (no init file).

Do you? If not, then recursively bisect your init file to find out what part of it is interfering. You can comment out a region of text using command comment-region. Comment out 1/2, then 3/4, 7/8,... until you locate the problem.

(A step-by-step recipe to reproduce a problem should include anything you've done to modify the default Emacs behavior, i.e., what you get using only emacs -Q.)