I have a folder with many Disney(R) movies. For a good 20% of those the preview shown by Dolphin is the classical Disney(R) movie blue intro screen, which of course is almost identical for all files. This makes thumbails useless (and my little daughter cannot choose which cartoon to watch by looking at the thumbnails!). It would be useful to have the option somewhere to reload (or set!) a specific preview for a single file. This would be best implemented by a right-click service menu but an option in the Properties menu would also be OK. I know one could manually delete the preview in the thumbnail folder, but it is not really the fastest way to do it, especially when you have many thumbnails and have to search through them. Reproducible: Always
Before Dolphin can offer such actions, the kio thumnailing system needs to support these features.
KDE-Look / KDE Improvements: http://kde-look.org/index.php?xsortmode=new&logpage=0&xcontentmode=37 has an alternative version of the standard KDE ffmpegthumbs - with it the user can - among other things: * can use external images as the thumbnails. * can use the KDE service menus to add/remove the thumbnails.
Oops - a link to the 'FFMpegThumbs-MattePaint': http://kde-look.org/content/show.php/FFMpegThumbs-MattePaint?content=153902
Looks like this feature is available via the referenced plugin.