Add option to run command on bell

Fixes #1528.

21 files changed, 292 insertions, 202 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c19894cb..ed7783ed 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -30,6 +30,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Expanding existing selections using the right mouse button
 - Support for `gopher` and `gemini` URLs
 - Unicode 13 support
+- Option to run command on bell which can be set in `bell.command`
 
 ### Changed
 
@@ -48,6 +49,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - To use the cell's text color for selection with a modified background, the `color.selection.text`
     variable must now be set to `CellForeground` instead of omitting it
 - URLs are no longer highlighted without a clearly delimited scheme
+- Renamed `visual_bell` to `bell`
 
 ### Fixed
 
diff --git a/Cargo.lock b/Cargo.lock
index 1fa52324..3acfb73b 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -32,6 +32,7 @@ dependencies = [
  "gl_generator 0.14.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "glutin 0.24.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "image 0.23.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.72 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "notify 4.0.15 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.10.2 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/alacritty.yml b/alacritty.yml
index ed6feafc..5a14a417 100644
--- a/alacritty.yml
+++ b/alacritty.yml
@@ -265,31 +265,46 @@
   #
   #indexed_colors: []
 
-# Visual Bell
-#
-# Any time the BEL code is received, Alacritty "rings" the visual bell. Once
-# rung, the terminal background will be set to white and transition back to the
-# default background color. You can control the rate of this transition by
-# setting the `duration` property (represented in milliseconds). You can also
-# configure the transition function by setting the `animation` property.
-#
-# Values for `animation`:
-#   - Ease
-#   - EaseOut
-#   - EaseOutSine
-#   - EaseOutQuad
-#   - EaseOutCubic
-#   - EaseOutQuart
-#   - EaseOutQuint
-#   - EaseOutExpo
-#   - EaseOutCirc
-#   - Linear
-#
-# Specifying a `duration` of `0` will disable the visual bell.
-#visual_bell:
-#  animation: EaseOutExpo
-#  duration: 0
-#  color: '#ffffff'
+# Bell
+#
+# The bell is rung every time the BEL control character is received.
+#bell:
+  # Visual Bell Animation
+  #
+  # Animation effect for flashing the screen when the visual bell is rung.
+  #
+  # Values for `animation`:
+  #   - Ease
+  #   - EaseOut
+  #   - EaseOutSine
+  #   - EaseOutQuad
+  #   - EaseOutCubic
+  #   - EaseOutQuart
+  #   - EaseOutQuint
+  #   - EaseOutExpo
+  #   - EaseOutCirc
+  #   - Linear
+  #animation: EaseOutExpo
+
+  # Duration of the visual bell flash. A `duration` of `0` will disable the
+  # visual bell animation.
+  #duration: 0
+
+  # Visual bell animation color.
+  #color: '#ffffff'
+
+  # Bell Command
+  #
+  # This program is executed whenever the bell is rung.
+  #
+  # When set to `command: None`, no command will be executed.
+  #
+  # Example:
+  #   command:
+  #     program: notify-send
+  #     args: ["Hello, World!"]
+  #
+  #command: None
 
 # Background opacity
 #
@@ -358,7 +373,7 @@
 #
 # Alacritty defaults to using the newer ConPTY backend if it is available,
 # since it resolves a lot of bugs and is quite a bit faster. If it is not
-# available, the the WinPTY backend will be used instead.
+# available, the WinPTY backend will be used instead.
 #
 # Setting this option to `true` makes Alacritty use the legacy WinPTY backend,
 # even if the ConPTY backend is available.
diff --git a/alacritty/Cargo.toml b/alacritty/Cargo.toml
index 6cd63867..9ed2d9ce 100644
--- a/alacritty/Cargo.toml
+++ b/alacritty/Cargo.toml
@@ -23,6 +23,7 @@ parking_lot = "0.10.2"
 font = { path = "../font", features = ["force_system_fontconfig"] }
 urlocator = "0.1.3"
 copypasta = { version = "0.7.0", default-features = false }
+libc = "0.2"
 unicode-width = "0.1"
 
 [build-dependencies]
diff --git a/alacritty/src/config/mod.rs b/alacritty/src/config/mod.rs
index f416039c..ffa7cbd3 100644
--- a/alacritty/src/config/mod.rs
+++ b/alacritty/src/config/mod.rs
@@ -217,6 +217,13 @@ fn print_deprecation_warnings(config: &Config) {
              the config"
         );
     }
+
+    if config.visual_bell.is_some() {
+        warn!(
+            target: LOG_TARGET_CONFIG,
+            "Config visual_bell has been deprecated; please use bell instead"
+        )
+    }
 }
 
 #[cfg(test)]
diff --git a/alacritty/src/config/monitor.rs b/alacritty/src/config/monitor.rs
index 42603c7e..2ed0c426 100644
--- a/alacritty/src/config/monitor.rs
+++ b/alacritty/src/config/monitor.rs
@@ -4,7 +4,7 @@ use std::time::Duration;
 
 use notify::{watcher, DebouncedEvent, RecursiveMode, Watcher};
 
-use alacritty_terminal::util;
+use alacritty_terminal::thread;
 
 use crate::event::{Event, EventProxy};
 
@@ -20,7 +20,7 @@ impl Monitor {
         let path = path.into();
 
         Monitor {
-            _thread: util::thread::spawn_named("config watcher", move || {
+            _thread: thread::spawn_named("config watcher", move || {
                 let (tx, rx) = mpsc::channel();
                 // The Duration argument is a debouncing period.
                 let mut watcher =
diff --git a/alacritty_terminal/src/util.rs b/alacritty/src/daemon.rs
index f996359a..4a6b6f83 100644
--- a/alacritty_terminal/src/util.rs
+++ b/alacritty/src/daemon.rs
@@ -1,34 +1,53 @@
 use std::ffi::OsStr;
+use std::fmt::Debug;
 use std::io;
-use std::process::{Command, Stdio};
-
 #[cfg(not(windows))]
 use std::os::unix::process::CommandExt;
-
 #[cfg(windows)]
 use std::os::windows::process::CommandExt;
+use std::process::{Command, Stdio};
+
+use log::{debug, warn};
+
 #[cfg(windows)]
 use winapi::um::winbase::{CREATE_NEW_PROCESS_GROUP, CREATE_NO_WINDOW};
 
-/// Threading utilities.
-pub mod thread {
-    /// Like `thread::spawn`, but with a `name` argument.
-    pub fn spawn_named<F, T, S>(name: S, f: F) -> std::thread::JoinHandle<T>
-    where
-        F: FnOnce() -> T + Send + 'static,
-        T: Send + 'static,
-        S: Into<String>,
-    {
-        std::thread::Builder::new().name(name.into()).spawn(f).expect("thread spawn works")
+/// Start the daemon and log error on failure.
+pub fn start_daemon<I, S>(program: &str, args: I)
+where
+    I: IntoIterator<Item = S> + Debug + Copy,
+    S: AsRef<OsStr>,
+{
+    match spawn_daemon(program, args) {
+        Ok(_) => debug!("Launched {} with args {:?}", program, args),
+        Err(_) => warn!("Unable to launch {} with args {:?}", program, args),
     }
+}
 
-    pub use std::thread::*;
+#[cfg(windows)]
+fn spawn_daemon<I, S>(program: &str, args: I) -> io::Result<()>
+where
+    I: IntoIterator<Item = S> + Copy,
+    S: AsRef<OsStr>,
+{
+    // Setting all the I/O handles to null and setting the
+    // CREATE_NEW_PROCESS_GROUP and CREATE_NO_WINDOW has the effect
+    // that console applications will run without opening a new
+    // console window.
+    Command::new(program)
+        .args(args)
+        .stdin(Stdio::null())
+        .stdout(Stdio::null())
+        .stderr(Stdio::null())
+        .creation_flags(CREATE_NEW_PROCESS_GROUP | CREATE_NO_WINDOW)
+        .spawn()
+        .map(|_| ())
 }
 
 #[cfg(not(windows))]
-pub fn start_daemon<I, S>(program: &str, args: I) -> io::Result<()>
+fn spawn_daemon<I, S>(program: &str, args: I) -> io::Result<()>
 where
-    I: IntoIterator<Item = S>,
+    I: IntoIterator<Item = S> + Copy,
     S: AsRef<OsStr>,
 {
     unsafe {
@@ -38,13 +57,13 @@ where
             .stdout(Stdio::null())
             .stderr(Stdio::null())
             .pre_exec(|| {
-                match ::libc::fork() {
+                match libc::fork() {
                     -1 => return Err(io::Error::last_os_error()),
                     0 => (),
-                    _ => ::libc::_exit(0),
+                    _ => libc::_exit(0),
                 }
 
-                if ::libc::setsid() == -1 {
+                if libc::setsid() == -1 {
                     return Err(io::Error::last_os_error());
                 }
 
@@ -55,23 +74,3 @@ where
             .map(|_| ())
     }
 }
-
-#[cfg(windows)]
-pub fn start_daemon<I, S>(program: &str, args: I) -> io::Result<()>
-where
-    I: IntoIterator<Item = S>,
-    S: AsRef<OsStr>,
-{
-    // Setting all the I/O handles to null and setting the
-    // CREATE_NEW_PROCESS_GROUP and CREATE_NO_WINDOW has the effect
-    // that console applications will run without opening a new
-    // console window.
-    Command::new(program)
-        .args(args)
-        .stdin(Stdio::null())
-        .stdout(Stdio::null())
-        .stderr(Stdio::null())
-        .creation_flags(CREATE_NEW_PROCESS_GROUP | CREATE_NO_WINDOW)
-        .spawn()
-        .map(|_| ())
-}
diff --git a/alacritty/src/display.rs b/alacritty/src/display.rs
index 53e6fc58..0a3bea34 100644
--- a/alacritty/src/display.rs
+++ b/alacritty/src/display.rs
@@ -540,7 +540,7 @@ impl Display {
                 0.,
                 size_info.width,
                 size_info.height,
-                config.visual_bell.color,
+                config.bell().color,
                 visual_bell_intensity as f32,
             );
             rects.push(visual_bell_rect);
diff --git a/alacritty/src/event.rs b/alacritty/src/event.rs
index edbc4086..f264aab5 100644
--- a/alacritty/src/event.rs
+++ b/alacritty/src/event.rs
@@ -3,6 +3,7 @@
 use std::borrow::Cow;
 use std::cmp::{max, min};
 use std::env;
+use std::fmt::Debug;
 #[cfg(unix)]
 use std::fs;
 use std::fs::File;
@@ -20,7 +21,7 @@ use glutin::event_loop::{ControlFlow, EventLoop, EventLoopProxy, EventLoopWindow
 use glutin::platform::desktop::EventLoopExtDesktop;
 #[cfg(not(any(target_os = "macos", windows)))]
 use glutin::platform::unix::EventLoopWindowTargetExtUnix;
-use log::{debug, info, warn};
+use log::info;
 use serde_json as json;
 
 #[cfg(target_os = "macos")]
@@ -38,12 +39,12 @@ use alacritty_terminal::term::cell::Cell;
 use alacritty_terminal::term::{ClipboardType, SizeInfo, Term, TermMode};
 #[cfg(not(windows))]
 use alacritty_terminal::tty;
-use alacritty_terminal::util::start_daemon;
 
 use crate::cli::Options;
 use crate::clipboard::Clipboard;
 use crate::config;
 use crate::config::Config;
+use crate::daemon::start_daemon;
 use crate::display::{Display, DisplayUpdate};
 use crate::input::{self, ActionContext as _, FONT_SIZE_STEP};
 use crate::scheduler::{Scheduler, TimerId};
@@ -290,10 +291,7 @@ impl<'a, N: Notify + 'a, T: EventListener> input::ActionContext<T> for ActionCon
         #[cfg(not(unix))]
         let args: Vec<String> = Vec::new();
 
-        match start_daemon(&alacritty, &args) {
-            Ok(_) => debug!("Started new Alacritty process: {} {:?}", alacritty, args),
-            Err(_) => warn!("Unable to start new Alacritty process: {} {:?}", alacritty, args),
-        }
+        start_daemon(&alacritty, &args);
     }
 
     /// Spawn URL launcher when clicking on URLs.
@@ -308,10 +306,7 @@ impl<'a, N: Notify + 'a, T: EventListener> input::ActionContext<T> for ActionCon
             let end = self.terminal.visible_to_buffer(url.end());
             args.push(self.terminal.bounds_to_string(start, end));
 
-            match start_daemon(launcher.program(), &args) {
-                Ok(_) => debug!("Launched {} with args {:?}", launcher.program(), args),
-                Err(_) => warn!("Unable to launch {} with args {:?}", launcher.program(), args),
-            }
+            start_daemon(launcher.program(), &args);
         }
     }
 
@@ -839,8 +834,10 @@ impl<N: Notify + OnResize> Processor<N> {
                 Event::TerminalEvent(event) => match event {
                     TerminalEvent::Title(title) => processor.ctx.window.set_title(&title),
                     TerminalEvent::Wakeup => processor.ctx.terminal.dirty = true,
-                    TerminalEvent::Urgent => {
-                        processor.ctx.window.set_urgent(!processor.ctx.terminal.is_focused)
+                    TerminalEvent::Bell => {
+                        let bell_command = processor.ctx.config.bell().command.as_ref();
+                        let _ = bell_command.map(|cmd| start_daemon(cmd.program(), cmd.args()));
+                        processor.ctx.window.set_urgent(!processor.ctx.terminal.is_focused);
                     },
                     TerminalEvent::ClipboardStore(clipboard_type, content) => {
                         processor.ctx.clipboard.store(clipboard_type, content);
diff --git a/alacritty/src/input.rs b/alacritty/src/input.rs
index 48450b12..cab0f0e2 100644
--- a/alacritty/src/input.rs
+++ b/alacritty/src/input.rs
@@ -10,7 +10,7 @@ use std::cmp::{max, min, Ordering};
 use std::marker::PhantomData;
 use std::time::{Duration, Instant};
 
-use log::{debug, trace, warn};
+use log::trace;
 
 use glutin::dpi::PhysicalPosition;
 use glutin::event::{
@@ -30,11 +30,11 @@ use alacritty_terminal::message_bar::{self, Message};
 use alacritty_terminal::selection::SelectionType;
 use alacritty_terminal::term::mode::TermMode;
 use alacritty_terminal::term::{ClipboardType, SizeInfo, Term};
-use alacritty_terminal::util::start_daemon;
 use alacritty_terminal::vi_mode::ViMotion;
 
 use crate::clipboard::Clipboard;
 use crate::config::{Action, Binding, Config, Key, ViAction};
+use crate::daemon::start_daemon;
 use crate::event::{ClickState, Event, Mouse, TYPING_SEARCH_DELAY};
 use crate::scheduler::{Scheduler, TimerId};
 use crate::url::{Url, Urls};
@@ -160,10 +160,7 @@ impl<T: EventListener> Execute<T> for Action {
                 let program = program.program();
                 trace!("Running command {} with args {:?}", program, args);
 
-                match start_daemon(program, args) {
-                    Ok(_) => debug!("Spawned new proc"),
-                    Err(err) => warn!("Couldn't run command {}", err),
-                }
+                start_daemon(program, args);
             },
             Action::ClearSelection => ctx.clear_selection(),
             Action::ToggleViMode => ctx.terminal_mut().toggle_vi_mode(),
diff --git a/alacritty/src/main.rs b/alacritty/src/main.rs
index ab4acaa7..9fbcab55 100644
--- a/alacritty/src/main.rs
+++ b/alacritty/src/main.rs
@@ -36,6 +36,7 @@ mod cli;
 mod clipboard;
 mod config;
 mod cursor;
+mod daemon;
 mod display;
 mod event;
 mod input;
diff --git a/alacritty/src/renderer/mod.rs b/alacritty/src/renderer/mod.rs
index 7dc037a1..bd9f4ae7 100644
--- a/alacritty/src/renderer/mod.rs
+++ b/alacritty/src/renderer/mod.rs
@@ -24,7 +24,7 @@ use alacritty_terminal::index::{Column, Line};
 use alacritty_terminal::term::cell::{self, Flags};
 use alacritty_terminal::term::color::Rgb;
 use alacritty_terminal::term::{self, CursorKey, RenderableCell, RenderableCellContent, SizeInfo};
-use alacritty_terminal::util;
+use alacritty_terminal::thread;
 use std::fmt::{self, Display, Formatter};
 
 pub mod rects;
@@ -660,7 +660,7 @@ impl QuadRenderer {
         let (msg_tx, msg_rx) = mpsc::channel();
 
         if cfg!(feature = "live-shader-reload") {
-            util::thread::spawn_named("live shader reload", move || {
+            thread::spawn_named("live shader reload", move || {
                 let (tx, rx) = std::sync::mpsc::channel();
                 // The Duration argument is a debouncing period.
                 let mut watcher =
diff --git a/alacritty_terminal/src/config/bell.rs b/alacritty_terminal/src/config/bell.rs
new file mode 100644
index 00000000..97010f31
--- /dev/null
+++ b/alacritty_terminal/src/config/bell.rs
@@ -0,0 +1,120 @@
+use std::time::Duration;
+
+use log::error;
+use serde::{Deserialize, Deserializer};
+use serde_yaml::Value;
+
+use crate::config::{failure_default, Program, LOG_TARGET_CONFIG};
+use crate::term::color::Rgb;
+
+const DEFAULT_BELL_COLOR: Rgb = Rgb { r: 255, g: 255, b: 255 };
+
+#[serde(default)]
+#[derive(Deserialize, Clone, Debug, PartialEq, Eq)]
+pub struct BellConfig {
+    /// Visual bell animation function.
+    #[serde(deserialize_with = "failure_default")]
+    pub animation: BellAnimation,
+
+    /// Visual bell duration in milliseconds.
+    #[serde(deserialize_with = "failure_default")]
+    duration: u16,
+
+    /// Visual bell flash color.
+    #[serde(deserialize_with = "deserialize_bell_color")]
+    pub color: Rgb,
+
+    /// Command to run on bell.
+    #[serde(deserialize_with = "deserialize_bell_command")]
+    pub command: Option<Program>,
+}
+
+impl Default for BellConfig {
+    fn default() -> Self {
+        Self {
+            animation: Default::default(),
+            duration: Default::default(),
+            command: Default::default(),
+            color: DEFAULT_BELL_COLOR,
+        }
+    }
+}
+
+impl BellConfig {
+    /// Visual bell duration in milliseconds.
+    #[inline]
+    pub fn duration(&self) -> Duration {
+        Duration::from_millis(u64::from(self.duration))
+    }
+}
+
+fn deserialize_bell_color<'a, D>(deserializer: D) -> Result<Rgb, D::Error>
+where
+    D: Deserializer<'a>,
+{
+    let value = Value::deserialize(deserializer)?;
+    match Rgb::deserialize(value) {
+        Ok(value) => Ok(value),
+        Err(err) => {
+            error!(
+                target: LOG_TARGET_CONFIG,
+                "Problem with config: {}, using default color value {}", err, DEFAULT_BELL_COLOR
+            );
+
+            Ok(DEFAULT_BELL_COLOR)
+        },
+    }
+}
+
+fn deserialize_bell_command<'a, D>(deserializer: D) -> Result<Option<Program>, D::Error>
+where
+    D: Deserializer<'a>,
+{
+    // Deserialize to generic value.
+    let val = Value::deserialize(deserializer)?;
+
+    // Accept `None` to disable the bell command.
+    if val.as_str().filter(|v| v.to_lowercase() == "none").is_some() {
+        return Ok(None);
+    }
+
+    match Program::deserialize(val) {
+        Ok(command) => Ok(Some(command)),
+        Err(err) => {
+            error!(target: LOG_TARGET_CONFIG, "Problem with config: {}; ignoring field", err);
+            Ok(None)
+        },
+    }
+}
+
+/// `VisualBellAnimations` are modeled after a subset of CSS transitions and Robert
+/// Penner's Easing Functions.
+#[derive(Clone, Copy, Debug, Deserialize, PartialEq, Eq)]
+pub enum BellAnimation {
+    // CSS animation.
+    Ease,
+    // CSS animation.
+    EaseOut,
+    // Penner animation.
+    EaseOutSine,
+    // Penner animation.
+    EaseOutQuad,
+    // Penner animation.
+    EaseOutCubic,
+    // Penner animation.
+    EaseOutQuart,
+    // Penner animation.
+    EaseOutQuint,
+    // Penner animation.
+    EaseOutExpo,
+    // Penner animation.
+    EaseOutCirc,
+    // Penner animation.
+    Linear,
+}
+
+impl Default for BellAnimation {
+    fn default() -> Self {
+        BellAnimation::EaseOutExpo
+    }
+}
diff --git a/alacritty_terminal/src/config/mod.rs b/alacritty_terminal/src/config/mod.rs
index e3d72fda..83dcd7b8 100644
--- a/alacritty_terminal/src/config/mod.rs
+++ b/alacritty_terminal/src/config/mod.rs
@@ -6,20 +6,20 @@ use log::error;
 use serde::{Deserialize, Deserializer};
 use serde_yaml::Value;
 
+mod bell;
 mod colors;
 mod debug;
 mod font;
 mod scrolling;
-mod visual_bell;
 mod window;
 
 use crate::ansi::CursorStyle;
 
+pub use crate::config::bell::{BellAnimation, BellConfig};
 pub use crate::config::colors::Colors;
 pub use crate::config::debug::Debug;
 pub use crate::config::font::{Font, FontDescription};
 pub use crate::config::scrolling::Scrolling;
-pub use crate::config::visual_bell::{VisualBellAnimation, VisualBellConfig};
 pub use crate::config::window::{Decorations, Dimensions, StartupMode, WindowConfig, DEFAULT_NAME};
 
 pub const LOG_TARGET_CONFIG: &str = "alacritty_config";
@@ -69,9 +69,9 @@ pub struct Config<T> {
     #[serde(default, deserialize_with = "failure_default")]
     pub config_path: Option<PathBuf>,
 
-    /// Visual bell configuration.
+    /// Bell configuration.
     #[serde(default, deserialize_with = "failure_default")]
-    pub visual_bell: VisualBellConfig,
+    bell: BellConfig,
 
     /// Use dynamic title.
     #[serde(default, deserialize_with = "failure_default")]
@@ -114,6 +114,10 @@ pub struct Config<T> {
     #[serde(skip)]
     pub hold: bool,
 
+    // TODO: DEPRECATED
+    #[serde(default, deserialize_with = "failure_default")]
+    pub visual_bell: Option<BellConfig>,
+
     // TODO: REMOVED
     #[serde(default, deserialize_with = "failure_default")]
     pub tabspaces: Option<usize>,
@@ -176,6 +180,11 @@ impl<T> Config<T> {
     pub fn background_opacity(&self) -> f32 {
         self.background_opacity.0 as f32
     }
+
+    #[inline]
+    pub fn bell(&self) -> &BellConfig {
+        self.visual_bell.as_ref().unwrap_or(&self.bell)
+    }
 }
 
 #[serde(default)]
diff --git a/alacritty_terminal/src/config/visual_bell.rs b/alacritty_terminal/src/config/visual_bell.rs
deleted file mode 100644
index 1a0a327b..00000000
--- a/alacritty_terminal/src/config/visual_bell.rs
+++ /dev/null
@@ -1,76 +0,0 @@
-use std::time::Duration;
-
-use serde::Deserialize;
-
-use crate::config::failure_default;
-use crate::term::color::Rgb;
-
-#[serde(default)]
-#[derive(Deserialize, Clone, Debug, PartialEq, Eq)]
-pub struct VisualBellConfig {
-    /// Visual bell animation function.
-    #[serde(deserialize_with = "failure_default")]
-    pub animation: VisualBellAnimation,
-
-    /// Visual bell duration in milliseconds.
-    #[serde(deserialize_with = "failure_default")]
-    pub duration: u16,
-
-    /// Visual bell flash color.
-    #[serde(deserialize_with = "failure_default")]
-    pub color: Rgb,
-}
-
-impl Default for VisualBellConfig {
-    fn default() -> VisualBellConfig {
-        VisualBellConfig {
-            animation: Default::default(),
-            duration: Default::default(),
-            color: default_visual_bell_color(),
-        }
-    }
-}
-
-impl VisualBellConfig {
-    /// Visual bell duration in milliseconds.
-    #[inline]
-    pub fn duration(&self) -> Duration {
-        Duration::from_millis(u64::from(self.duration))
-    }
-}
-
-/// `VisualBellAnimations` are modeled after a subset of CSS transitions and Robert
-/// Penner's Easing Functions.
-#[derive(Clone, Copy, Debug, Deserialize, PartialEq, Eq)]
-pub enum VisualBellAnimation {
-    // CSS animation.
-    Ease,
-    // CSS animation.
-    EaseOut,
-    // Penner animation.
-    EaseOutSine,
-    // Penner animation.
-    EaseOutQuad,
-    // Penner animation.
-    EaseOutCubic,
-    // Penner animation.
-    EaseOutQuart,
-    // Penner animation.
-    EaseOutQuint,
-    // Penner animation.
-    EaseOutExpo,
-    // Penner animation.
-    EaseOutCirc,
-    // Penner animation.
-    Linear,
-}
-
-impl Default for VisualBellAnimation {
-    fn default() -> Self {
-        VisualBellAnimation::EaseOutExpo
-    }
-}
-
-fn default_visual_bell_color() -> Rgb {
-    Rgb { r: 255, g: 255, b: 255 }
-}
diff --git a/alacritty_terminal/src/event.rs b/alacritty_terminal/src/event.rs
index 296e3bb0..863a2fbf 100644
--- a/alacritty_terminal/src/event.rs
+++ b/alacritty_terminal/src/event.rs
@@ -11,7 +11,7 @@ pub enum Event {
     ClipboardStore(ClipboardType, String),
     ClipboardLoad(ClipboardType, Arc<dyn Fn(&str) -> String + Sync + Send + 'static>),
     Wakeup,
-    Urgent,
+    Bell,
     Exit,
 }
 
@@ -23,7 +23,7 @@ impl Debug for Event {
             Event::ClipboardStore(ty, text) => write!(f, "ClipboardStore({:?}, {})", ty, text),
             Event::ClipboardLoad(ty, _) => write!(f, "ClipboardLoad({:?})", ty),
             Event::Wakeup => write!(f, "Wakeup"),
-            Event::Urgent => write!(f, "Urgent"),
+            Event::Bell => write!(f, "Bell"),
             Event::Exit => write!(f, "Exit"),
         }
     }
diff --git a/alacritty_terminal/src/event_loop.rs b/alacritty_terminal/src/event_loop.rs
index 46216605..156510b0 100644
--- a/alacritty_terminal/src/event_loop.rs
+++ b/alacritty_terminal/src/event_loop.rs
@@ -6,6 +6,7 @@ use std::fs::File;
 use std::io::{self, ErrorKind, Read, Write};
 use std::marker::Send;
 use std::sync::Arc;
+use std::thread::JoinHandle;
 
 use log::error;
 #[cfg(not(windows))]
@@ -18,8 +19,8 @@ use crate::config::Config;
 use crate::event::{self, Event, EventListener};
 use crate::sync::FairMutex;
 use crate::term::{SizeInfo, Term};
+use crate::thread;
 use crate::tty;
-use crate::util::thread;
 
 /// Max bytes to read from the PTY.
 const MAX_READ: usize = 0x10_000;
@@ -300,7 +301,7 @@ where
         Ok(())
     }
 
-    pub fn spawn(mut self) -> thread::JoinHandle<(Self, State)> {
+    pub fn spawn(mut self) -> JoinHandle<(Self, State)> {
         thread::spawn_named("PTY reader", move || {
             let mut state = State::default();
             let mut buf = [0u8; MAX_READ];
diff --git a/alacritty_terminal/src/lib.rs b/alacritty_terminal/src/lib.rs
index 1d2fe551..7130218b 100644
--- a/alacritty_terminal/src/lib.rs
+++ b/alacritty_terminal/src/lib.rs
@@ -22,8 +22,8 @@ pub mod panic;
 pub mod selection;
 pub mod sync;
 pub mod term;
+pub mod thread;
 pub mod tty;
-pub mod util;
 pub mod vi_mode;
 
 pub use crate::grid::Grid;
diff --git a/alacritty_terminal/src/term/color.rs b/alacritty_terminal/src/term/color.rs
index f20601d6..9aeb7061 100644
--- a/alacritty_terminal/src/term/color.rs
+++ b/alacritty_terminal/src/term/color.rs
@@ -1,4 +1,4 @@
-use std::fmt;
+use std::fmt::{self, Display, Formatter};
 use std::ops::{Index, IndexMut, Mul};
 use std::str::FromStr;
 
@@ -64,7 +64,7 @@ impl<'de> Deserialize<'de> for Rgb {
         impl<'a> Visitor<'a> for RgbVisitor {
             type Value = Rgb;
 
-            fn expecting(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+            fn expecting(&self, f: &mut Formatter<'_>) -> fmt::Result {
                 f.write_str("hex color like #ff00ff")
             }
 
@@ -94,6 +94,12 @@ impl<'de> Deserialize<'de> for Rgb {
     }
 }
 
+impl Display for Rgb {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        write!(f, "#{:02x}{:02x}{:02x}", self.r, self.g, self.b)
+    }
+}
+
 impl FromStr for Rgb {
     type Err = ();
 
diff --git a/alacritty_terminal/src/term/mod.rs b/alacritty_terminal/src/term/mod.rs
index d59838d4..f3f22d47 100644
--- a/alacritty_terminal/src/term/mod.rs
+++ b/alacritty_terminal/src/term/mod.rs
@@ -14,7 +14,7 @@ use unicode_width::UnicodeWidthChar;
 use crate::ansi::{
     self, Attr, CharsetIndex, Color, CursorStyle, Handler, NamedColor, StandardCharset,
 };
-use crate::config::{Config, VisualBellAnimation};
+use crate::config::{BellAnimation, BellConfig, Config};
 use crate::event::{Event, EventListener};
 use crate::grid::{Dimensions, DisplayIter, Grid, IndexRegion, Indexed, Scroll};
 use crate::index::{self, Boundary, Column, Direction, IndexRange, Line, Point, Side};
@@ -467,7 +467,7 @@ pub use crate::term::mode::TermMode;
 
 pub struct VisualBell {
     /// Visual bell animation.
-    animation: VisualBellAnimation,
+    animation: BellAnimation,
 
     /// Visual bell duration.
     duration: Duration,
@@ -484,15 +484,6 @@ fn cubic_bezier(p0: f64, p1: f64, p2: f64, p3: f64, x: f64) -> f64 {
 }
 
 impl VisualBell {
-    pub fn new<C>(config: &Config<C>) -> VisualBell {
-        let visual_bell_config = &config.visual_bell;
-        VisualBell {
-            animation: visual_bell_config.animation,
-            duration: visual_bell_config.duration(),
-            start_time: None,
-        }
-    }
-
     /// Ring the visual bell, and return its intensity.
     pub fn ring(&mut self) -> f64 {
         let now = Instant::now();
@@ -557,19 +548,17 @@ impl VisualBell {
                 // VisualBell. When `time` is 0.0, `inverse_intensity` is 0.0,
                 // and when `time` is 1.0, `inverse_intensity` is 1.0.
                 let inverse_intensity = match self.animation {
-                    VisualBellAnimation::Ease | VisualBellAnimation::EaseOut => {
+                    BellAnimation::Ease | BellAnimation::EaseOut => {
                         cubic_bezier(0.25, 0.1, 0.25, 1.0, time)
                     },
-                    VisualBellAnimation::EaseOutSine => cubic_bezier(0.39, 0.575, 0.565, 1.0, time),
-                    VisualBellAnimation::EaseOutQuad => cubic_bezier(0.25, 0.46, 0.45, 0.94, time),
-                    VisualBellAnimation::EaseOutCubic => {
-                        cubic_bezier(0.215, 0.61, 0.355, 1.0, time)
-                    },
-                    VisualBellAnimation::EaseOutQuart => cubic_bezier(0.165, 0.84, 0.44, 1.0, time),
-                    VisualBellAnimation::EaseOutQuint => cubic_bezier(0.23, 1.0, 0.32, 1.0, time),
-                    VisualBellAnimation::EaseOutExpo => cubic_bezier(0.19, 1.0, 0.22, 1.0, time),
-                    VisualBellAnimation::EaseOutCirc => cubic_bezier(0.075, 0.82, 0.165, 1.0, time),
-                    VisualBellAnimation::Linear => time,
+                    BellAnimation::EaseOutSine => cubic_bezier(0.39, 0.575, 0.565, 1.0, time),
+                    BellAnimation::EaseOutQuad => cubic_bezier(0.25, 0.46, 0.45, 0.94, time),
+                    BellAnimation::EaseOutCubic => cubic_bezier(0.215, 0.61, 0.355, 1.0, time),
+                    BellAnimation::EaseOutQuart => cubic_bezier(0.165, 0.84, 0.44, 1.0, time),
+                    BellAnimation::EaseOutQuint => cubic_bezier(0.23, 1.0, 0.32, 1.0, time),
+                    BellAnimation::EaseOutExpo => cubic_bezier(0.19, 1.0, 0.22, 1.0, time),
+                    BellAnimation::EaseOutCirc => cubic_bezier(0.075, 0.82, 0.165, 1.0, time),
+                    BellAnimation::Linear => time,
                 };
 
                 // Since we want the `intensity` of the VisualBell to decay over
@@ -580,9 +569,19 @@ impl VisualBell {
     }
 
     pub fn update_config<C>(&mut self, config: &Config<C>) {
-        let visual_bell_config = &config.visual_bell;
-        self.animation = visual_bell_config.animation;
-        self.duration = visual_bell_config.duration();
+        let bell_config = config.bell();
+        self.animation = bell_config.animation;
+        self.duration = bell_config.duration();
+    }
+}
+
+impl From<&BellConfig> for VisualBell {
+    fn from(bell_config: &BellConfig) -> VisualBell {
+        VisualBell {
+            animation: bell_config.animation,
+            duration: bell_config.duration(),
+            start_time: None,
+        }
     }
 }
 
@@ -763,7 +762,7 @@ impl<T> Term<T> {
 
         Term {
             dirty: false,
-            visual_bell: VisualBell::new(config),
+            visual_bell: config.bell().into(),
             grid,
             inactive_grid: alt,
             active_charset: Default::default(),
@@ -1617,7 +1616,7 @@ impl<T: EventListener> Handler for Term<T> {
     fn bell(&mut self) {
         trace!("Bell");
         self.visual_bell.ring();
-        self.event_proxy.send_event(Event::Urgent);
+        self.event_proxy.send_event(Event::Bell);
     }
 
     #[inline]
diff --git a/alacritty_terminal/src/thread.rs b/alacritty_terminal/src/thread.rs
new file mode 100644
index 00000000..6a93b78d
--- /dev/null
+++ b/alacritty_terminal/src/thread.rs
@@ -0,0 +1,11 @@
+use std::thread::{Builder, JoinHandle};
+
+/// Like `thread::spawn`, but with a `name` argument.
+pub fn spawn_named<F, T, S>(name: S, f: F) -> JoinHandle<T>
+where
+    F: FnOnce() -> T + Send + 'static,
+    T: Send + 'static,
+    S: Into<String>,
+{
+    Builder::new().name(name.into()).spawn(f).expect("thread spawn works")
+}