The preview cache is not updated after changing the wallpaper (simple picture jpg and png) on the Activity switcher.


Reproducible: Always

Steps to Reproduce:
1) Having several activities with different wallpapers (jpg or png)
2) Open activity switcher - see activities with wallpapers thumbnails
3) Change wallpaper on 1 or all activities
4) Do nothing or restart PC (doesn't matter)
5) Open activity switcher - see activities with old wallpapers thumbnails

Actual Results:  
Those wallpapers thumbnails are not updated.

Expected Results:  
Those wallpapers thumbnails should be updated using the currents wallpapers.

I deleted the following file
 ~/.cache/activityswitcher_wallpaper_preview.kcache
 and restarted to refresh the cache

I've seen the following bug:
 https://bugs.kde.org/show_bug.cgi?id=360034
It give the process:
Open konsole, and write the following kquitapp5 plasmashell
rm ~/.cache/activityswitcher_wallpaper_preview.kcache
plasmashell &>/dev/null&