patch 8.1.1321: no docs or tests for listener functions commit https://github.com/vim/vim/commit/a334772967de25764ed7b11d768e8b977818d0c6 Author: Bram Moolenaar <Bram@vim.org> Date: Sat May 11 21:14:24 2019 +0200 patch 8.1.1321: no docs or tests for listener functions Problem: No docs or tests for listener functions. Solution: Add help and tests for listener_add() and listener_remove(). Invoke the callbacks before redrawing.