Comment 1 for bug 1776736

Aside from flat out not working, the current functionality of this is extraordinarily clunky even if the edits were savable. The main use case for this is to copy information from a record or records to be merged into the lead record. In the XUL client you can have all the records to be merged side by side and open to the flat text editor which allows you to easily copy information from one record to another.

Here, in order to access the flat text editor for the Lead record you have use "Edit using full editor" which opens in a window on top of the merging window, so you can no longer see or copy from the other records.