Weird cursor behaviour when non-English characters are typed

When characters like "ä", "ö" or "å" are typed in the editor, the showable cursor shifts 2 times to the right (one time more than it should). However, the characters typed after this will not appear right before the showable cursor, but two or more columns to the left depending on how many non-English characters you have typed. I didn't investigate what was causing this problem.