x11/wayland: fix ctrl-key for latin layouts

This is fixing a regression introduced by the fix for #2845.
The resolution for this is relatively straightforward, but took a bit
of effort to plumb.

Previously:
* CTRL/ALT/SUPER-modified keys with no explicit expansion would end
  up just taking the US layout version of the key.  That worked well
  for the intended problem with non-latin layouts, but for eg: German
  layouts it caused expansion to totally the wrong thing

Now:
* CTRL/ALT/SUPER-modified keys which effectively expand to non-ascii
  text (eg: cyrillic "Es") now take the equivalent key press from the
  US layout (which would be "c" in the "Es" case).  For European
  layouts this heuristic seems to avoid unexpected effects, but could
  do with some validation from native users.

To support this, the xkb code splits the `Keyboard` struct out from
some of the higher level logic and introduces a `KeyboardWithFallback`
struct that is built out of the user-selected keyboard layout, and
the fallback keyboard.  Now the fallback keyboard is fed the same
key inputs as the selected keyboard to correctly model the key
combinations.

refs: #3610
refs: #3933

docs/changelog.md

@@ -57,6 +57,9 @@ As features stabilize some brief notes about them will accumulate here.
 
 * Modals, such as `CharSelect` and `CommandPalette` did not respect alternative
   OS-level key maps. #3470
+* X11/Wayland: CTRL-key presses for non-US latin keymaps regressed due to
+  changes to [improve handling of CTRL-key presses for non-latin
+  layouts](https://github.com/wez/wezterm/issues/2845). #3610
 * Numerous issues with the kitty keyboard protocol implementation #2546 #3220
   #3315 #3473 #3474 #3476 #3478 #3479 #3484 #3526
 * mux: Attempting to spawn into an ad-hoc SSH domain after the last tab could

window/src/os/wayland/connection.rs

@@ -4,7 +4,7 @@ use super::window::*;
 use crate::connection::ConnectionOps;
 use crate::os::wayland::inputhandler::InputHandler;
 use crate::os::wayland::output::OutputHandler;
-use crate::os::x11::keyboard::Keyboard;
+use crate::os::x11::keyboard::KeyboardWithFallback;
 use crate::screen::{ScreenInfo, Screens};
 use crate::spawn::*;
 use crate::{Appearance, Connection, ScreenRect, WindowEvent};
@@ -56,7 +56,7 @@ pub struct WaylandConnection {
     // must be ahead of the rest.
     pub(crate) gl_connection: RefCell<Option<Rc<crate::egl::GlConnection>>>,
     pub(crate) pointer: RefCell<PointerDispatcher>,
-    pub(crate) keyboard_mapper: RefCell<Option<Keyboard>>,
+    pub(crate) keyboard_mapper: RefCell<Option<KeyboardWithFallback>>,
     pub(crate) keyboard_window_id: RefCell<Option<usize>>,
     pub(crate) surface_to_window_id: RefCell<HashMap<u32, usize>>,
     pub(crate) active_surface_id: RefCell<u32>,
@@ -265,7 +265,7 @@ impl WaylandConnection {
                             data.pop();
                         }
                         let s = String::from_utf8(data)?;
-                        match Keyboard::new_from_string(s) {
+                        match KeyboardWithFallback::new_from_string(s) {
                             Ok(k) => {
                                 self.keyboard_mapper.replace(Some(k));
                             }

window/src/os/wayland/window.rs

@@ -4,7 +4,7 @@ use super::pointer::*;
 use crate::connection::ConnectionOps;
 use crate::os::wayland::connection::WaylandConnection;
 use crate::os::wayland::wl_id;
-use crate::os::x11::keyboard::Keyboard;
+use crate::os::x11::keyboard::KeyboardWithFallback;
 use crate::{
     Appearance, Clipboard, Connection, Dimensions, MouseCursor, Point, Rect,
     RequestedWindowGeometry, ResolvedGeometry, ScreenPoint, Window, WindowEvent, WindowEventSender,
@@ -484,7 +484,7 @@ impl WaylandWindowInner {
         }
     }
 
-    fn emit_focus(&mut self, mapper: &mut Keyboard, focused: bool) {
+    fn emit_focus(&mut self, mapper: &mut KeyboardWithFallback, focused: bool) {
         // Clear the modifiers when we change focus, otherwise weird
         // things can happen.  For instance, if we lost focus because
         // CTRL+SHIFT+N was pressed to spawn a new window, we'd be

window/src/os/x11/connection.rs

@@ -1,4 +1,4 @@
-use super::keyboard::Keyboard;
+use super::keyboard::{Keyboard, KeyboardWithFallback};
 use crate::connection::ConnectionOps;
 use crate::os::x11::window::XWindowInner;
 use crate::os::x11::xsettings::*;
@@ -25,7 +25,7 @@ pub struct XConnection {
     pub(crate) xsettings: RefCell<XSettingsMap>,
     pub screen_num: i32,
     pub root: xcb::x::Window,
-    pub keyboard: Keyboard,
+    pub keyboard: KeyboardWithFallback,
     pub kbd_ev: u8,
     pub atom_protocols: Atom,
     pub cursor_font_id: xcb::x::Font,
@@ -639,6 +639,7 @@ impl XConnection {
             visual.blue_mask()
         );
         let (keyboard, kbd_ev) = Keyboard::new(&conn)?;
+        let keyboard = KeyboardWithFallback::new(keyboard)?;
 
         let cursor_font_id = conn.generate_id();
         let cursor_font_name = "cursor";