Created attachment 159046 [details]
Snapshot of how excess line breaks look when editing a title clip

Kdenlive adds line breaks to title clips by writing additional 
 strings for each line break in each title clip (and also at the end of the lines of "/item", "startviewport rect", "endviewport rect", "background color" and "/kdenlivetitle" as seen when opening the .kdenlive file with a plain text editor) every time a .kdenlive file is saved.


STEPS TO REPRODUCE
1. open an existing .kdenlive file with any amount of title clips
2. modify the .kdenlive file
3. Save the file.
4. Close kdenlive
5. Reopen kdenlive
6. Reopen the same .kdenlive file
7. Right click on a title clip and select "Edit clip".

OBSERVED RESULT
Excess line breaks in title clips caused by 
 strings, not visible in the preview or in a processed file, but visible when opening a title clip, additional 
 strings visible in a plain text editor.

EXPECTED RESULT
Having only the original line breaks of the file (visible in a plain text editor as mere line breaks on Windows).

SOFTWARE/OS VERSIONS
Windows: 10
KDE Frameworks Version: 5.105.0
Qt Version: 5.15.9

ADDITIONAL INFORMATION
MLT version: 7.15.0