Ensure tasks are properly terminated on close, fix incorrect mutex in thumbnailcache causing corruption

Eric Jiang authored Aug 15, 2022 and Jean-Baptiste Mardelle committed Sep 05, 2022

The Kdenlive UI allows you to add multiple spaces between words in
subtitles. This displays correctly in the UI and is preserved when
saving the SRT file, but the spaces are removed when opening the SRT
file.

Changing line.simplified() to line.trimmed() seems to fix the round-trip
issue.

BUG: 457878

@frdbr @emohr

Related to #1499

This reverts commit db4ac94b.

This reverts commit f8f8000f.

Massimo Stella authored Aug 02, 2022 and Julius Künzel committed Aug 04, 2022

(cherry picked from commit fff370e0)

Related to #1494

Related to #1320