Your very appropriate broad hint to use google set me thinking, Anisha Kaul
. While the google-search produced several very much linux approaches I was trying to alter dolphins behaviour. So I searched the KDE docs
and came up with this:
The first points to the removable devices page of the control center. I checked the boxes as I thought correctly but the expected results in the "directories" view didn't materialize. It was late in the night and I was too tired to probe further but the functionality is obviously there, taken care of by the developers (thanks!).
The second is the dolphin documentation. There is a chapter which explains that one can pull folders into the "places" view. If need be, I can construct the functionality I want from this feature (pulling the folders from the"directories" view while hiding the devices of "places"). Thus I'd get a panel with an immediate reaction to a device freshly plugged in.
In conclusion: I can get the function I want. It might be necessary to adapt dolphin by hand. Thanks everybody for your input