Add scrolloff option for completion window.

doc/cmp.txt

@@ -609,6 +609,12 @@ window.{completion,documentation}.zindex~
   The completion window's zindex.
   See |nvim_open_win|.
 
+                        *cmp-config.window.{completion,documentation}.scrolloff*
+window.completion.scrolloff~
+  `number`
+  Specify the window's scrolloff option.
+  See |'scrolloff'|.
+
                                        *cmp-config.window.completion.col_offset*
 window.completion.col_offset~
   `number`

lua/cmp/config/default.lua

@@ -91,6 +91,7 @@ return function()
       completion = {
         border = { '', '', '', '', '', '', '', '' },
         winhighlight = 'Normal:Pmenu,FloatBorder:Pmenu,CursorLine:PmenuSel,Search:None',
+        scrolloff = 0,
         col_offset = 0,
         side_padding = 1,
       },

lua/cmp/config/window.lua

@@ -6,6 +6,7 @@ window.bordered = function(opts)
     border = opts.border or 'rounded',
     winhighlight = opts.winhighlight or 'Normal:Normal,FloatBorder:Normal,CursorLine:Visual,Search:None',
     zindex = opts.zindex or 1001,
+    scrolloff = opts.scrolloff or 0,
     col_offset = opts.col_offset or 0,
     side_padding = opts.side_padding or 1,
   }

lua/cmp/types/cmp.lua

@@ -116,6 +116,7 @@ cmp.ItemField = {
 ---@field public zindex integer|nil
 ---@field public max_width integer|nil
 ---@field public max_height integer|nil
+---@field public scrolloff integer|nil
 
 ---@class cmp.ConfirmationConfig
 ---@field public default_behavior cmp.ConfirmBehavior

lua/cmp/view/custom_entries_view.lua

@@ -30,7 +30,6 @@ custom_entries_view.new = function()
   self.entries_win:option('cursorlineopt', 'line')
   self.entries_win:option('foldenable', false)
   self.entries_win:option('wrap', false)
-  self.entries_win:option('scrolloff', 0)
   -- This is done so that strdisplaywidth calculations for lines in the
   -- custom_entries_view window exactly match with what is really displayed,
   -- see comment in cmp.Entry.get_view. Setting tabstop to 1 makes all tabs be
@@ -195,6 +194,7 @@ custom_entries_view.open = function(self, offset, entries)
   -- Apply window options (that might be changed) on the custom completion menu.
   self.entries_win:option('winblend', vim.o.pumblend)
   self.entries_win:option('winhighlight', completion.winhighlight)
+  self.entries_win:option('scrolloff', completion.scrolloff)
   self.entries_win:open({
     relative = 'editor',
     style = 'minimal',