Can't get Ctrl+Left/RightArrow to work inside the terminal

[dinvlad]

Hi folks, new WezTerm user here, -

I'm using LazyVim, which has the following default mappings for resizing windows in NeoVim:

map("n", "<C-Left>", "<cmd>vertical resize -2<cr>", { desc = "Decrease window width" })
map("n", "<C-Right>", "<cmd>vertical resize +2<cr>", { desc = "Increase window width" })

However, unlike their Ctrl+Up/Down counterparts, they don't appear to work inside WezTerm. When I completely disable the default WezTerm bindings using config.disable_default_key_bindings = true, they start working again, which suggests this is indeed an issue with WezTerm defaults, and not something else.

When I view the relevant mappings

$ wezterm show-keys --lua | grep -E '(LeftArrow|RightArrow|keys|key_tables|mode)'     
  keys = {
    { key = 'LeftArrow', mods = 'SHIFT|CTRL', action = act.ActivatePaneDirection 'Left' },
    { key = 'LeftArrow', mods = 'SHIFT|ALT|CTRL', action = act.AdjustPaneSize{ 'Left', 1 } },
    { key = 'RightArrow', mods = 'SHIFT|CTRL', action = act.ActivatePaneDirection 'Right' },
    { key = 'RightArrow', mods = 'SHIFT|ALT|CTRL', action = act.AdjustPaneSize{ 'Right', 1 } },
  key_tables = {
    copy_mode = {
      { key = 'LeftArrow', mods = 'NONE', action = act.CopyMode 'MoveLeft' },
      { key = 'LeftArrow', mods = 'ALT', action = act.CopyMode 'MoveBackwardWord' },
      { key = 'RightArrow', mods = 'NONE', action = act.CopyMode 'MoveRight' },
      { key = 'RightArrow', mods = 'ALT', action = act.CopyMode 'MoveForwardWord' },
    search_mode = {

they don't seem to include Ctrl+Left/RightArrow explicitly. However, I've tried disabling all of these nevertheless, using

config.keys = {
	-- Disable defaults
	{ key = "LeftArrow", mods = "SHIFT|CTRL", action = act.DisableDefaultAssignment },
	{ key = "LeftArrow", mods = "SHIFT|ALT|CTRL", action = act.DisableDefaultAssignment },
	{ key = "RightArrow", mods = "SHIFT|CTRL", action = act.DisableDefaultAssignment },
	{ key = "RightArrow", mods = "SHIFT|ALT|CTRL", action = act.DisableDefaultAssignment },
	{ key = "LeftArrow", mods = "NONE", action = act.DisableDefaultAssignment },
	{ key = "LeftArrow", mods = "ALT", action = act.DisableDefaultAssignment },
	{ key = "RightArrow", mods = "NONE", action = act.DisableDefaultAssignment },
	{ key = "RightArrow", mods = "ALT", action = act.DisableDefaultAssignment },
	-- Disable target bindings, just in case
	{ key = "LeftArrow", mods = "CTRL", action = act.DisableDefaultAssignment },
	{ key = "RightArrow", mods = "CTRL", action = act.DisableDefaultAssignment },
}

I then see this:

$ wezterm show-keys --lua | grep -E '(LeftArrow|RightArrow|keys|key_tables|mode)'
  keys = {
  key_tables = {
    copy_mode = {
      { key = 'LeftArrow', mods = 'NONE', action = act.CopyMode 'MoveLeft' },
      { key = 'LeftArrow', mods = 'ALT', action = act.CopyMode 'MoveBackwardWord' },
      { key = 'RightArrow', mods = 'NONE', action = act.CopyMode 'MoveRight' },
      { key = 'RightArrow', mods = 'ALT', action = act.CopyMode 'MoveForwardWord' },
    search_mode = {

so as you can see, most of them got disabled. However, this doesn't seem to help the issue.

Additionally, when I run wezterm --config debug_key_events=true, Ctrl+Up/DownArrow events do get logged, but Ctrl+Left/RightArrow don't, as if they're not detected by WezTerm at all.

One other thing I've noticed is WezTerm's menu has Window -> Select Tab -> Activate the tab to the right assigned to ^-> by default - even though I cannot find that binding among the default bindings, as you can see above. When I disable it as above though, this assignment disappears, but that doesn't help the issue.

All of this is on macOS Ventura 13.4.1, if that matters.

Thanks in advance for any help!

EDIT: I've looked at other issues prior to posting this, but only now found one that seems relevant: #3508

[cstrahan]

I'm running into precisely the same problem.

Tried these mappings (looked at https://sw.kovidgoyal.net/kitty/keyboard-protocol to figure out the right encoding):

  { key = 'LeftArrow', mods = 'CTRL', action = act.SendString '\x1b\x5b1;5D' },
  { key = 'RightArrow', mods = 'CTRL', action = act.SendString '\x1b\x5b1;5C' },

Used the kitten command that comes with the kitty terminal emulator (kitten show_key -m kitty) but it looks like CTRL+{LEFT,RIGHT} aren't sent by wezterm, even with the above key maps.

[cstrahan]

If you can tolerate using SHFT+CTRL instead of just CTRL (easy enough for me, since I map capslock to control I can roll my pinky over both the shift and control keys), this works:

  { key = 'LeftArrow', mods = 'SHIFT|CTRL', action = act.SendString '\x1b\x5b1;5D' },
  { key = 'RightArrow', mods = 'SHIFT|CTRL', action = act.SendString '\x1b\x5b1;5C' },

But then you'll sacrifice the ability to send SHIFT+CTRL modifiers with the left/right arrow keys. You could make a different sacrifice by using 'SUPER|CTRL' as the modifiers instead.

Another problem comes to light though, as kitten show_key -m kitty shows:

ctrl+RIGHT PRESS
CSI 1 ; 5 C

shift+ctrl+RIGHT RELEASE
CSI 1 ; 6 : 3 C

Using SendString as part of a key mapping will send the correct key press code, but letting go will result in sending the release code for the actually held keys. This could confuse a terminal app that keeps track of held/released key state, though this doesn't apply in the neovim case as it is only looking for key presses and ignores the releases.

Perhaps wezterm could use a way to override the key release code as part of an extended SendString action, or something along those lines.