What steps will reproduce the problem? 1. Change the selection in the line ending drop-down in the serial monitor. 2. Restart Arduino. 3. Re-open the serial monitor.

What is the expected output? What do you see instead?

The old line ending selection should be preserved, but it's not, because we don't save it in the preferences.

In addition, the default line ending is 'none', which makes it impossible to do line-oriented input.

https://github.com/arduino/Arduino/commit/5e028ea09d93a04343386385a529dc65321f6198