Add a default shortcut for visually focusing windows

Fixes #4110

docs/basic.rst

@@ -57,6 +57,7 @@ Previous window             :sc:`previous_window`
 Move window forward         :sc:`move_window_forward`
 Move window backward        :sc:`move_window_backward`
 Move window to top          :sc:`move_window_to_top`
+Visually focus window       :sc:`focus_visible_window`
 Focus specific window       :sc:`first_window`, :sc:`second_window` ... :sc:`tenth_window`
                             (also :kbd:`⌘+1`, :kbd:`⌘+2` ... :kbd:`⌘+9` on macOS)
                             (clockwise from the top-left)

docs/changelog.rst

@@ -12,6 +12,10 @@ To update |kitty|, :doc:`follow the instructions <binary>`.
   output of the last command in a new window, etc. See :ref:`shell_integration`
   for details.
 
+- A new shortcut :sc:`focus_visible_window` to visually focus a window using
+  the keyboard. Pressing it causes numbers to appear over each visible window
+  and you can press the number to focus the corresponding window (:iss:`4110`)
+
 - A new option :opt:`tab_bar_align` to draw the tab bar centered or right
   aligned (:iss:`3946`)