options: allow different highlights in windows

src/nvim/options.lua

@@ -2701,6 +2701,14 @@ return {
       varname='p_wak',
       defaults={if_true={vi="menu"}}
     },
+    {
+      full_name='winhighlight', abbreviation='winhl',
+      type='string', scope={'window'},
+      vi_def=true,
+      alloced=true,
+      redraw={'current_window'},
+      defaults={if_true={vi=""}}
+    },
     {
       full_name='window', abbreviation='wi',
       type='number', scope={'global'},