When the "solo" button (the button with a headphones icon) is clicked, it isolates audio from a single track. When it is then clicked on another track, it isolates the other track only. Instead, in (audio) multitrack editors I know of, it would select _also_ the other track, and would allow to quickly listen to two (or a small number) of tracks together, while silencing the rest. Currently, the only way to do this is to go over the trackline and manually silence all other tracks. SOFTWARE/OS VERSIONS Linux/KDE Plasma: Debian buster, appimage Kdenlive
That is how I expect the solo to work, but maybe adding a function when shift clicking to add more than one track would make sense in a situation with many tracks.