termwiz: request xterm modifyOtherKeys

When in raw mode, go to level 2, but use level 1 for cooked
so that we don't obfuscate ctrl-c.

A consequnce of this is that CTRL-C is now reported to the app
as CTRL-lowercase-c where we previously reported as CTRL-uppercase-C.
Made a note of the breaking nature of this change in a new changelog
file.

Fixed recognizing SHIFT-TAB

refs: https://github.com/wez/wezterm/issues/2511

termwiz/CHANGELOG.md

@@ -0,0 +1,7 @@
+
+main:
+
+* BREAKING: We now request modifyOtherKeys when setting up the unix terminal.
+  As a consequence, CTRL keys like `CTRL-C` are now reported as
+  `CTRL-lower-case-c` rather than `CTRL-upper-case-C`. We do this even when
+  modifyOtherKeys isn't active for the sake of overall consistency.

termwiz/examples/key_tester.rs

@@ -4,7 +4,7 @@ use termwiz::terminal::{new_terminal, Terminal};
 use termwiz::Error;
 
 const CTRL_C: KeyEvent = KeyEvent {
-    key: KeyCode::Char('C'),
+    key: KeyCode::Char('c'),
     modifiers: Modifiers::CTRL,
 };
 

termwiz/src/input.rs

@@ -1167,7 +1167,7 @@ impl InputParser {
             map.insert(
                 &ctrl,
                 InputEvent::Key(KeyEvent {
-                    key: KeyCode::Char(alpha as char),
+                    key: KeyCode::Char((alpha as char).to_ascii_lowercase()),
                     modifiers: Modifiers::CTRL,
                 }),
             );
@@ -1416,6 +1416,13 @@ impl InputParser {
                 modifiers: Modifiers::NONE,
             }),
         );
+        map.insert(
+            b"\x1b[Z",
+            InputEvent::Key(KeyEvent {
+                key: KeyCode::Tab,
+                modifiers: Modifiers::SHIFT,
+            }),
+        );
 
         map.insert(
             &[b'\r'],
@@ -1724,7 +1731,7 @@ mod test {
             vec![
                 InputEvent::Key(KeyEvent {
                     modifiers: Modifiers::CTRL,
-                    key: KeyCode::Char('C'),
+                    key: KeyCode::Char('c'),
                 }),
                 InputEvent::Key(KeyEvent {
                     modifiers: Modifiers::ALT,

termwiz/src/terminal/unix.rs

@@ -18,7 +18,7 @@ use termios::{
 };
 
 use crate::caps::Capabilities;
-use crate::escape::csi::{DecPrivateMode, DecPrivateModeCode, Mode, CSI};
+use crate::escape::csi::{DecPrivateMode, DecPrivateModeCode, Mode, XtermKeyModifierResource, CSI};
 use crate::input::{InputEvent, InputParser};
 use crate::render::terminfo::TerminfoRenderer;
 use crate::surface::Change;
@@ -99,6 +99,17 @@ impl TtyWriteHandle {
         }
         Ok(())
     }
+
+    fn modify_other_keys(&mut self, level: i64) -> std::io::Result<()> {
+        write!(
+            self,
+            "{}",
+            CSI::Mode(Mode::XtermKeyMode {
+                resource: XtermKeyModifierResource::OtherKeys,
+                value: Some(level),
+            })
+        )
+    }
 }
 
 impl Write for TtyWriteHandle {
@@ -323,12 +334,14 @@ impl Terminal for UnixTerminal {
             decset!(AnyEventMouse);
             decset!(SGRMouse);
         }
+        self.write.modify_other_keys(2)?;
         self.write.flush()?;
 
         Ok(())
     }
 
     fn set_cooked_mode(&mut self) -> Result<()> {
+        self.write.modify_other_keys(1)?;
         self.write
             .set_termios(&self.saved_termios, SetAttributeWhen::Now)
     }
@@ -515,6 +528,7 @@ impl Drop for UnixTerminal {
             decreset!(SGRMouse);
             decreset!(AnyEventMouse);
         }
+        self.write.modify_other_keys(0).unwrap();
         self.exit_alternate_screen().unwrap();
         self.write.flush().unwrap();