?? I right click IN the search term area (no icons...)
Right click is the CONTEXT MENU for the area. It works as described in both Windows and Linux (My main machine is now Linux Mint as a SATA port took out my SSD boot block)
Contexts menuS are all over Calibre (and most other programs).
Right click various places and see what pops up

Maybe my tendency to context use comes from when I started using PC's (1979-80)