There are as much a 3 bug reports that I've come across in the recent days that come down to one reason. The reason is the code for T285956: Lock selection to a single side in TableDiffFormatter (part of the solution for T285285: Community Wishlist Survey 2021/Editing/Copy and paste from diffs) that introduced this line of code:
document.getSelection().removeAllRanges();
(@Daimona). It seems to be the immediate reason of the issues.
The reports themselves were:
- Dragging and dropping text selected in diffs doesn't work (link).
- On diff pages, one cannot use Shift+click to extend the selected text (by @stjn).
- In Convenient-Discussions one cannot choose an autocomplete item because the text input loses the selection (I've fixed that in the script already) (by @MBH).