Xcode 10: Control-T behaves incorrectly at the end of a line

Number:rdar://50826693 Date Originated:2019-05-15
Status:Open Resolved:
Product:Developer Tools/Xcode Product Version:10.2.1
Classification:UI/Usability Reproducible:Always
The text editor in Xcode 10 does not handle Control-T correctly, at least when it comes to the very important special case of Control-T at the end of the line.  In NSTextView fields, and in Emacs generally back to at least 1979 (when I first encountered it), Control-T at the end of the line exchanges the last two characters of the line; this is a special case, but much more useful than the alternative of exchanging the character at the end of the line with the newline, thereby moving the last character onto the following line.

Sadly, this is what the text editor in Xcode 10 does.  Not only is this behavior inconsistent and unexpected, but it has no inherent utility.

Steps to Reproduce:
In Xcode 10, open a new empty text file; type several characters (e.g. "12345"), then press control-T.

Expected Results:
The last two characters in the line (in other words, the two characters before the insertion point) are exchanged. (In the preceding example, the result would be "12354".)

Actual Results:
The last character in the line is moved to the start of the following line.


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