This is the screen shot of Entries tab in System tray settings:
I can toggle the status and click Apply but nothing happens and on reopening system tray settings all entries are reverted to the original status as shown here.
Since one of them, Clipboard, is set to “Shown” it’s probably an old KDE4 setting overriding Plasma 5, but what and where is it and how to stop it from interfering?
OTOH, Clipboard is from “System Services” category while I actually want to toggle Dropbox, which is “Application Status”.
On that note - what is painting Dropbox icon background purple? The icon itself is transparent. Should I start a separate thread for this Dropbox issue? Its icon stands out as a sore thumb in system tray and never matches the panel. When panel is black the icon is purple, when panel was light the icon was black. Is it Dropbox itself adding color as well as status emblem, or is it drawing background according to some obscure Plasma settings?