When I use Cmd+K to go to the next occurrence of the selected word, Eclipse leaves behind these red "cursors" right before the copies of the word that I navigate through. If I then edit the last occurrence that I find, Eclipse "helpfully" edits all the occurrences that I've navigated through in the same way. This leaves corruption in parts of my file that I'm not currently looking at, which is really infuriating.
I want to disable this "feature", but I haven't got a clue what to call it, so I don't know how to find the setting that turns it off. Searching the Eclipse preferences for "occurrence" only gives various versions of "Mark Occurrences" for each editor plugin, which doesn't disable this behavior when unchecked.
EDIT: Here's a video displaying the behavior I'm talking about: https://youtu.be/8xeKRLyGSLg
This isn't really given by PyDev, it's a feature added by LiClipse (http://www.liclipse.com/multi_edition_video.html).
After the link is done with Ctrl+K, you can press ESC to remove those links if you don't want the multi-edition to happen (so that when you edit one occurrence you don't edit the others).
I must say this is the first request to have that turned off... I'm pretty certain as I just took a look and there's no setting to do that -- so, unfortunately, until the next release, you have to either live with it, remembering to press ESC if you don't want the multi edition to happen or use a plain Eclipse install with PyDev, but you'd also be without other LiClipse benefits, such as textmate bundles, vertical indent guides, theming integration, etc.
Still, note that ideally, I'd say you should get used to it as it can be a real time-saver -- although I'll implement the setting to turn it off for the next release anyways, as it's something that should really be there ;)