Adapted from my posting at english wikipedia Village Pump (technical):
Hi, I have suffered in my editing for about a week, since the rollout of new editor interface (wikitext editor) which I am using now. Very frequently, but not always, when I try to insert a capital letter or any character which involves the shift key (including the colon character, angle brackets, squiggly brackets at least on my keyboard), the cursor jumps to the left/beginning of the paragraph. It is exasperating! This is using Chrome browser in a Windows 10 environment, with whatever javascript or whatever user-specific settings that I have and don't particularly know about. What is going on? It seems worse editing in the Imicrosoft edge browser. It doesn't happen much in new text entry; it is horrible when I am trying to edit a reference or other template call. Help! --doncram 22:52, 20 October 2017 (UTC)
(I was informed by editor PrimeHunter that "The new editor interface is a beta feature and not default. You can get the normal source editor by disabling "Automatically enable all new beta features" and "New wikitext mode" at Special:Preferences#mw-prefsection-betafeatures. , and I have now turned that off. But this feedback is to provide developers with my notice.)
FYI, I was sort of liking the editor's ability to switch between modes, it was getting me to try visual editing sometimes. But in my case I needed to use the source editor mode mostly, because I was pasting in incomplete references then trying to fill out the fields. For example, it was impossible to change "|accessdate=2017" to "|accessdate=October 20, 2017", say, except for by indirect editing (i.e. creating capital "O" elsewhere and copy-pasting it into place. I hope this sort of helps somehow. --~~~~