Test setup:

Load this page in a webengine based browser
Make sure QWebEngineSettings.WebAttribute.JavascriptCanAccessClipboard is set to true

Have the ability to inspect your X11 clipboards like this shell function


    printf "primary  : %s\nclipboard: %s\n" "$(xclip -o)" "$(xclip -o -selection clipboard)"

Now go through the below steps and inspect the clipboard after each one:

First set both clipboards to the same known value: highlight line one and copy with ctrl+c. Your clipboards should now display:
```
      primary  : Line one: highlight and copy me
      clipboard: Line one: highlight and copy me
      
```
Now highlight line two to change the primary selection to be different from the clipboard. Your clipboards should now display:
```
      primary  : Line two: only highlight me
      clipboard: Line one: highlight and copy me
      
```
Now press the button the will copy to the clipboard. On QtWebEngine 6.6.1 (and all previous versions as far as i can remember) your clipboards should display the following:
```
      primary  : clipboard text
      clipboard: clipboard text
      
```

The problem is that on the 6.7 branch only the clipboard will get updated, the primary selection will stay as "Line two":
```
    primary  : Line two: only highlight me  <== this is a change in behaviour
    clipboard: clipboard text
    
```

Line one: highlight and copy me

Line two: only highlight me