Don't set the background color when initializing with transparency

Cargo.toml

@@ -137,7 +137,6 @@ features = [
     "NSApplication",
     "NSBitmapImageRep",
     "NSButton",
-    "NSColor",
     "NSControl",
     "NSCursor",
     "NSDragging",

src/changelog/unreleased.md

@@ -260,3 +260,4 @@ changelog entry.
 - On Wayland, fix decoration glitch on close with some compositors.
 - On Android, fix a regression introduced in #2748 to allow volume key events to be received again.
 - On Windows, don't return a valid window handle outside of the GUI thread.
+- On macOS, don't set the background color when initializing a window with transparency.

src/platform_impl/macos/window_delegate.rs

@@ -12,7 +12,7 @@ use objc2::{
 };
 use objc2_app_kit::{
     NSAppKitVersionNumber, NSAppKitVersionNumber10_12, NSAppearance, NSApplication,
-    NSApplicationPresentationOptions, NSBackingStoreType, NSColor, NSDraggingDestination,
+    NSApplicationPresentationOptions, NSBackingStoreType, NSDraggingDestination,
     NSFilenamesPboardType, NSPasteboard, NSRequestUserAttentionType, NSScreen, NSView,
     NSWindowButton, NSWindowDelegate, NSWindowFullScreenButton, NSWindowLevel,
     NSWindowOcclusionState, NSWindowOrderingMode, NSWindowSharingType, NSWindowStyleMask,
@@ -605,7 +605,6 @@ fn new_window(attrs: &WindowAttributes, mtm: MainThreadMarker) -> Option<Id<Wini
 
         if attrs.transparent {
             window.setOpaque(false);
-            window.setBackgroundColor(Some(unsafe { &NSColor::clearColor() }));
         }
 
         // register for drag and drop operations.

src/window.rs

@@ -941,6 +941,8 @@ impl Window {
     ///
     /// ## Platform-specific
     ///
+    /// - **macOS:** If you're not drawing to the window yourself, you might have to set the
+    ///   background color of the window to enable transparency.
     /// - **Web / iOS / Android:** Unsupported.
     /// - **X11:** Can only be set while building the window, with
     ///   [`WindowAttributes::with_transparent`].