2 files changed, 25 insertions, 0 deletions
diff --git a/alacritty/src/display.rs b/alacritty/src/display.rs
index 1fe1d2de..fb82b9f8 100644
--- a/alacritty/src/display.rs
+++ b/alacritty/src/display.rs
@@ -610,6 +610,12 @@ impl Display {
         #[cfg(all(feature = "wayland", not(any(target_os = "macos", windows))))]
         self.request_frame(&self.window);
 
+        // Clear window shadows to prevent shadow artifacts on macOS.
+        #[cfg(target_os = "macos")]
+        if config.ui_config.background_opacity() < 1.0 {
+            self.window.invalidate_shadow();
+        }
+
         self.window.swap_buffers();
 
         #[cfg(all(feature = "x11", not(any(target_os = "macos", windows))))]
diff --git a/alacritty/src/window.rs b/alacritty/src/window.rs
index f4a38183..1b874d15 100644
--- a/alacritty/src/window.rs
+++ b/alacritty/src/window.rs
@@ -31,6 +31,8 @@ use {
 
 use std::fmt::{self, Display, Formatter};
 
+#[cfg(target_os = "macos")]
+use cocoa::base::id;
 use glutin::dpi::{PhysicalPosition, PhysicalSize};
 use glutin::event_loop::EventLoop;
 #[cfg(target_os = "macos")]
@@ -41,6 +43,10 @@ use glutin::window::{
     CursorIcon, Fullscreen, UserAttentionType, Window as GlutinWindow, WindowBuilder, WindowId,
 };
 use glutin::{self, ContextBuilder, PossiblyCurrent, WindowedContext};
+#[cfg(target_os = "macos")]
+use objc::{msg_send, sel, sel_impl};
+#[cfg(target_os = "macos")]
+use raw_window_handle::{HasRawWindowHandle, RawWindowHandle};
 #[cfg(windows)]
 use winapi::shared::minwindef::WORD;
 
@@ -435,6 +441,19 @@ impl Window {
         self.windowed_context.resize(size);
     }
 
+    /// Force macOS to clear shadow of transparent windows.
+    #[cfg(target_os = "macos")]
+    pub fn invalidate_shadow(&self) {
+        let raw_window = match self.window().raw_window_handle() {
+            RawWindowHandle::MacOS(handle) => handle.ns_window as id,
+            _ => return,
+        };
+
+        unsafe {
+            let _: () = msg_send![raw_window, invalidateShadow];
+        }
+    }
+
     fn window(&self) -> &GlutinWindow {
         self.windowed_context.window()
     }