Set a default icon for all eframe apps: a white `e` on black background (#2996)

As a user you can change this by setting `NativeOptions::icon_data`.
Set it to `None` to get the default icon assigned by the OS.

crates/eframe/Cargo.toml

@@ -11,7 +11,13 @@ readme = "README.md"
 repository = "https://github.com/emilk/egui/tree/master/crates/eframe"
 categories = ["gui", "game-development"]
 keywords = ["egui", "gui", "gamedev"]
-include = ["../LICENSE-APACHE", "../LICENSE-MIT", "**/*.rs", "Cargo.toml"]
+include = [
+  "../LICENSE-APACHE",
+  "../LICENSE-MIT",
+  "**/*.rs",
+  "Cargo.toml",
+  "data/icon.png",
+]
 
 [package.metadata.docs.rs]
 all-features = true

crates/eframe/src/epi/mod.rs

@@ -260,10 +260,10 @@ pub struct NativeOptions {
     /// [drag_and_drop]: https://docs.rs/winit/latest/x86_64-pc-windows-msvc/winit/platform/windows/trait.WindowBuilderExtWindows.html#tymethod.with_drag_and_drop
     pub drag_and_drop_support: bool,
 
-    /// The application icon, e.g. in the Windows task bar etc.
+    /// The application icon, e.g. in the Windows task bar or the alt-tab menu.
     ///
-    /// This doesn't work on Mac and on Wayland.
-    /// See <https://docs.rs/winit/latest/winit/window/struct.Window.html#method.set_window_icon> for more.
+    /// The default icon is a white `e` on a black background (for "egui" or "eframe").
+    /// If you prefer the OS default, set this to `None`.
     pub icon_data: Option<IconData>,
 
     /// The initial (inner) position of the native window in points (logical pixels).
@@ -414,8 +414,12 @@ impl Default for NativeOptions {
             #[cfg(target_os = "macos")]
             fullsize_content: false,
 
+            // We set a default "egui" or "eframe" icon, which is usually more distinctive than the default OS icon.
+            icon_data: Some(
+                IconData::try_from_png_bytes(&include_bytes!("../../data/icon.png")[..]).unwrap(),
+            ),
+
             drag_and_drop_support: true,
-            icon_data: None,
             initial_window_pos: None,
             initial_window_size: None,
             min_window_size: None,

crates/egui_demo_app/src/main.rs

@@ -22,11 +22,6 @@ fn main() -> Result<(), eframe::Error> {
 
         initial_window_size: Some([1280.0, 1024.0].into()),
 
-        icon_data: Some(
-            eframe::IconData::try_from_png_bytes(&include_bytes!("../../../media/icon.png")[..])
-                .unwrap(),
-        ),
-
         #[cfg(feature = "wgpu")]
         renderer: eframe::Renderer::Wgpu,