1689942 - Lines are glued when inserting a text fragment

Status: UNCONFIRMED

(Thunderbird :: Message Compose Window, enhancement)

Description

[GSV4]

Attachment: My screenshots

User Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.141 Safari/537.36 OPR/73.0.3856.344

Steps to reproduce:

1. I create a new email.
2. I create a new text file, in which I enter 3 lines: "Line 1", "Line 2" and "Line 3".
3. I enable the option "View \ Show Symbol \ Show All Characters" to make it clearer to you.
4. I select all the lines in the file and copy them.
5. I insert the lines in the email.
6. I press the "Enter" key.
7. In the file, I select the 2nd and 3rd lines and copy them.
8. In the letter, I select the 2nd and 3rd lines and insert the text.

Actual results:

The 2nd line is glued together with the 1st.

Expected results:

Nothing should change in the text of the message, because I replaced 2 lines in it with the same 2 lines from the buffer.