patch 8.0.1547: undo in the options window makes it empty commit https://github.com/vim/vim/commit/9c474b277336235012f0c058bbaef2961d1ec83e Author: Bram Moolenaar <Bram@vim.org> Date: Tue Feb 27 17:04:25 2018 +0100 patch 8.0.1547: undo in the options window makes it empty Problem: Undo in the options window makes it empty. Solution: Set 'undolevels' while filling the buffer. (Yasuhiro Matthew, closes #2645)