Add a mappable action to toggle the mirrored setting for the tall and fat layouts

Fixes #5344

docs/changelog.rst

@@ -60,6 +60,9 @@ Detailed list of changes
 - macOS: Fix a regression that caused switching keyboard input using Eisu and
   Kana keys not working (:iss:`5232`)
 
+- Add a mappable action to toggle the mirrored setting for the tall and fat
+  layouts (:pull:`5344`)
+
 - Wayland: Reduce flicker at startup by not using render frames immediately after a resize (:iss:`5235`)
 
 - Linux: Update cursor position after all key presses not just pre-edit text

docs/layouts.rst

@@ -68,10 +68,13 @@ for the options is::
     └──────────────┴───────────────┘
 
 In addition, you can map keys to increase or decrease the number of full-height
-windows, for example::
+windows, or toggle the mirrored setting, for example::
 
    map ctrl+[ layout_action decrease_num_full_size_windows
    map ctrl+] layout_action increase_num_full_size_windows
+   map ctrl+/ layout_action mirror toggle
+   map ctrl+y layout_action mirror true
+   map ctrl+n layout_action mirror false
 
 
 The Fat Layout

kitty/layout/tall.py

@@ -203,6 +203,18 @@ class Tall(Layout):
             if self.layout_opts.full_size > 1:
                 self.layout_opts.full_size -= 1
                 return True
+        if action_name == 'mirror':
+            action = (args or ('toggle',))[0]
+            ok = False
+            if action == 'toggle':
+                self.layout_opts.mirrored = not self.layout_opts.mirrored
+                ok = True
+            else:
+                new_val = to_bool(action)
+                if new_val != self.layout_opts.mirrored:
+                    self.layout_opts.mirrored = new_val
+                    ok = True
+            return ok
         return None
 
     def minimal_borders(self, all_windows: WindowList) -> Generator[BorderLine, None, None]: