SUMMARY A mention of the default Compose Key <Shift+Control R> - the right hand Control key - can neither be found in the KDE Documentation nor, in the KDE Wiki. STEPS TO REPRODUCE 1. Use it - <Shift+Control R>; release; type Compose sequence. 2. If the Compose sequence is correct, the character appears - in a Konsole window and, in a Firefox Browser (GtK) input box. OBSERVED RESULT Firefox examples right here - (1 3): ⅓ - (O /): Ø - (1 9): ⅑ EXPECTED RESULT Exactly as the observed result but, where is that documented? SOFTWARE/OS VERSIONS Linux/KDE Plasma: (available in About System) KDE Plasma Version: 5.18.6 KDE Frameworks Version: 5.71.0 Qt Version: 5.12.7 ADDITIONAL INFORMATION Discussion here in the openSUSE Forums: <https://forums.opensuse.org/showthread.php/552921-How-to-set-up-and-use-compose-key-in-KDE-Plasma> Please note that, my Keyboard is a Cherry CyMotion Linux 105-key German device. * The <AltGr> key is “ISO Level3 Shift”. * The right hand “Windows” key is <Super R> and, CyMotion Linux specific - not usable as an alternative Compose Key assignment.
No KDE code sets a default Compose key. You need to choose one for yourself in System Settiungs > Input Devices > Keyboard > Advanced tab > Position of Compose key. Personally I have my Caps Lock cay re-bound to be a Compose key. Maybe your distro sets one automatically? In this case, you would want to talk to your dist about it.