Created an extra command, to implement appropriat cmd+w behaviour on mac.

data/core/commands/root.lua

@@ -11,6 +11,15 @@ local t = {
     node:close_active_view(core.root_view.root_node)
   end,
 
+  ["root:close-or-quit"] = function()
+    local node = core.root_view:get_active_node()
+    if node and (not node:is_empty() or not node.is_primary_node) then
+      node:close_active_view(core.root_view.root_node)
+    else
+      core.quit()
+    end
+  end,
+
   ["root:close-all"] = function()
     core.confirm_close_all(core.root_view.close_all_docviews, core.root_view)
   end,

data/core/keymap-macos.lua

@@ -17,7 +17,8 @@ local function keymap_macos(keymap)
     ["cmd+ctrl+i"] = "root:switch-to-up",
     ["cmd+ctrl+k"] = "root:switch-to-down",
 
-    ["cmd+w"] = "root:close",
+
+    ["cmd+w"] = "root:close-or-quit",
     ["ctrl+tab"] = "root:switch-to-next-tab",
     ["ctrl+shift+tab"] = "root:switch-to-previous-tab",
     ["cmd+pageup"] = "root:move-tab-left",
@@ -31,7 +32,6 @@ local function keymap_macos(keymap)
     ["cmd+7"] = "root:switch-to-tab-7",
     ["cmd+8"] = "root:switch-to-tab-8",
     ["cmd+9"] = "root:switch-to-tab-9",
-
     ["cmd+f"] = "find-replace:find",
     ["cmd+r"] = "find-replace:replace",
     ["f3"] = "find-replace:repeat-find",

data/core/rootview.lua

@@ -584,7 +584,7 @@ end
 
 function Node:is_empty()
   if self.type == "leaf" then
-    return #self.views == 0
+    return #self.views == 0 or (#self.views == 1 and self.views[1]:is(EmptyView))
   else
     return self.a:is_empty() and self.b:is_empty()
   end