I would like to display emblem-mounted on icons .desktop files belonging to mounted devices. I know I can choose different icons for mounted and unmounted devices using the Icon= and UnmountIcon= lines, however current icon sets don't include separate icons for all kinds of mounted devices anymore (but a separate emblem-mounted icon instead). How do I tell dolphin to display that emblem on the normal icon when the device is mounted?

And how do I activate email notification for specific topics (instead of whole forums) -_-

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Ah thanks, well hidden! (and not visible before logged in)
Unfortunately, I don't really understand how the action manager can help with the emblems. Ok, it allows me to execute commands when the device becomes (un)mounted, but I still don't know how I get an emblem on the .desktop file (i.e. which command to run).

This would need to be handled programatically. I would recommend filing a feature request at bugs.kde.org.