Redraw vi cursor if tmux pane focus changes

Fixes #4788.

share/functions/__fish_config_interactive.fish

@@ -234,6 +234,20 @@ function __fish_config_interactive -d "Initializations that should be performed
         __fish_enable_bracketed_paste
     end
 
+    # Similarly, enable TMUX's focus reporting when in tmux.
+    # This will be handled by
+    # - The keybindings (reading the sequence and triggering an event)
+    # - Any listeners (like the vi-cursor)
+    if set -q TMUX
+        function __fish_enable_focus --on-event fish_postexec
+            echo \e\[\?1004h
+        end
+        function __fish_disable_focus --on-event fish_preexec
+            echo \e\[\?1004l
+        end
+        __fish_enable_focus
+    end
+
     function __fish_winch_handler --on-signal WINCH -d "Repaint screen when window changes size"
         commandline -f repaint >/dev/null 2>/dev/null
     end

share/functions/__fish_shared_key_bindings.fish

@@ -107,6 +107,16 @@ function __fish_shared_key_bindings -d "Bindings shared between emacs and vi mod
     bind --preset $argv \ee edit_command_buffer
     bind --preset $argv \ev edit_command_buffer
 
+
+    # Tmux' focus events.
+    # Exclude paste mode because that should get _everything_ literally.
+    for mode in (bind --list-modes | string match -v paste)
+        # We only need the in-focus event currently (to redraw the vi-cursor).
+        bind -M $mode \e\[I 'emit fish_focus_in'
+        bind -M $mode \e\[O false
+        bind -M $mode \e\[\?1004h false
+    end
+
     # Support for "bracketed paste"
     # The way it works is that we acknowledge our support by printing
     # \e\[?2004h

share/functions/fish_default_key_bindings.fish

@@ -84,11 +84,6 @@ function fish_default_key_bindings -d "Default (Emacs-like) key bindings for fis
 
     bind --preset $argv \ed kill-word
 
-    # Ignore some known-bad control sequences
-    # https://github.com/fish-shell/fish-shell/issues/1917
-    bind --preset $argv \e\[I 'begin;end'
-    bind --preset $argv \e\[O 'begin;end'
-
     # term-specific special bindings
     switch "$TERM"
         case 'rxvt*'

share/functions/fish_vi_cursor.fish

@@ -107,7 +107,7 @@ function fish_vi_cursor -d 'Set cursor shape for different vi modes'
     or set -g fish_cursor_unknown block blink
 
     echo "
-          function fish_vi_cursor_handle --on-variable fish_bind_mode --on-event fish_postexec
+          function fish_vi_cursor_handle --on-variable fish_bind_mode --on-event fish_postexec --on-event fish_focus_in
               set -l varname fish_cursor_\$fish_bind_mode
               if not set -q \$varname
                 set varname fish_cursor_unknown