(Follow-up to #15308, which added ^C Interrupt Execution to doc and Shell menu, and to #27120, which proposed to add ^/ Toggle Highlighting, until I realized that that should be part of #6858, about highlighting non-.py files.)
Every IDLE function should be documented. More should be on menu. Perhaps add Move/delete menus for cursor movement and directional deletion, if not a diagram.
Another idea. A searchable current key binding list, possible sortable by key as well as function. It should include fixed builtin bindings as well as extension bindings. See #27120 for motivation.
Side issue 1: Menu entries for extensions do not reflect customization (? verify, from Roger).
Side issue 2: Menus need to be tested.