fix: Use winborder for window menu and fix scrollbar window (#2158)

Author: Aqothy

lua/cmp/config/default.lua

@@ -1,5 +1,6 @@
 local compare = require('cmp.config.compare')
 local types = require('cmp.types')
+local window = require('cmp.config.window')
 
 local WIDE_HEIGHT = 40
 
@@ -107,7 +108,7 @@ return function()
 
     window = {
       completion = {
-        border = { '', '', '', '', '', '', '', '' },
+        border = window.get_border(),
         winhighlight = 'Normal:Pmenu,FloatBorder:Pmenu,CursorLine:PmenuSel,Search:None',
         winblend = vim.o.pumblend,
         scrolloff = 0,
@@ -118,7 +119,7 @@ return function()
       documentation = {
         max_height = math.floor(WIDE_HEIGHT * (WIDE_HEIGHT / vim.o.lines)),
         max_width = math.floor((WIDE_HEIGHT * 2) * (vim.o.columns / (WIDE_HEIGHT * 2 * 16 / 9))),
-        border = { '', '', '', ' ', '', '', '', ' ' },
+        border = window.get_border(),
         winhighlight = 'FloatBorder:NormalFloat',
         winblend = vim.o.pumblend,
       },

lua/cmp/config/window.lua

@@ -13,4 +13,13 @@ window.bordered = function(opts)
   }
 end
 
+window.get_border = function()
+  -- On neovim 0.11+, use the vim.o.winborder option by default
+  local has_winborder, winborder = pcall(function() return vim.o.winborder end)
+  if has_winborder and winborder ~= '' then return winborder end
+
+  -- On lower versions return the default
+  return 'none'
+end
+
 return window