What does this improve?
- Do not create too many KIO::MimetypeJob for each file
- Do not call `DropJob::setApplicationActions()` too many times/ create too many menus for each drop.
+ Currently, when you have the desktop in the Desktop layout, if you drop 10 jpg files into the desktop, it creates 10 menus at the same position.
+ when you have the desktop in the Folder layout, if you drop 10 jpg files into the desktop, it calls `KIO::setApplicationActions()` 10 times.