SUMMARY There are two actions (New Tab, New Tab) that want to use the same shortcut (Ctrl+T). This is most probably a bug. Please report it in bugs.kde.org STEPS TO REPRODUCE 1. apt install dolphin 2. click on dolphin icon 3. OBSERVED RESULT popup window with the text in the summary EXPECTED RESULT SOFTWARE/OS VERSIONS Windows: macOS: Linux/KDE Plasma: (available in About System) KDE Plasma Version: KDE Frameworks Version: Qt Version: ADDITIONAL INFORMATION
This was fixed in Dolphin 18.08.2. Did Debian *really* ship with 18.08.0 and not provide the 18.08.2 bugfix minor release to its users? :/ If so, please go bug the Debian packagers to do that. *** This bug has been marked as a duplicate of bug 398324 ***