egui_glium: add support for transparent windows

Also support non-decorated windows (without border)

egui_glium/CHANGELOG.md

@@ -9,18 +9,15 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 
 ## 0.10.0 - 2021-02-28
-
 * [Add shaders for GLSL 1.2, GLSL ES 1.0 and 3.0](https://github.com/emilk/egui/pull/187)
   - now `egui` works well on old hardware which supports OpenGL 2.1 only like Raspberry Pi 1 and Zero.
 
 
 ## 0.9.0 - 2021-02-07
-
 * Nothing new
 
 
 ## 0.8.0 - 2021-01-17
-
 ### Fixed 🐛
 
 * Fix a bug where key releases weren't sent to egui
@@ -28,39 +25,31 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 
 ## 0.7.0 - 2021-01-04
-
 ### Changed
-
 * `http` `persistence` and `time` are now optional (and opt-in) features.
 
 
 ## 0.6.0 - 2020-12-26
-
 ### Added
-
 * `egui_glium` will auto-save your app state every 30 seconds.
 * `egui_glium` can now set windows as fixed size (e.g. the user can't resize the window). See `egui::App::is_resizable()`.
 
 ### Changed
-
 * `egui_glium` will now save you app state to [a better directory](https://docs.rs/directories-next/2.0.0/directories_next/struct.ProjectDirs.html#method.data_dir).
 * `egui_glium::run`: the parameter `app` now has signature `Box<dyn App>` (you need to add `Box::new(app)` to your code).
 * Window title is now passed via the `trait` function `egui::App::name()`.
 
 ### Fixed 🐛
-
 * Serialize window size in logical points instead of physical pixels.
 * Window position is now restored on restart.
 
+
 ## 0.5.0 - 2020-12-13
-
 ### Changed
-
 * FileStorage::from_path now takes `Into<Path>` instead of `String`
 
 
 ## 0.4.0 - 2020-11-28
-
 Started changelog. Features:
 
 * Input

egui_glium/src/backend.rs

@@ -56,19 +56,19 @@ impl epi::RepaintSignal for GliumRepaintSignal {
 }
 
 fn create_display(
-    title: &str,
-    initial_size_points: Option<Vec2>,
+    app: &dyn epi::App,
     window_settings: Option<WindowSettings>,
-    is_resizable: bool,
     window_icon: Option<glutin::window::Icon>,
     event_loop: &glutin::event_loop::EventLoop<RequestRepaintEvent>,
 ) -> glium::Display {
     let mut window_builder = glutin::window::WindowBuilder::new()
-        .with_decorations(true)
-        .with_resizable(is_resizable)
-        .with_title(title)
+        .with_decorations(app.decorated())
+        .with_resizable(app.is_resizable())
+        .with_title(app.name())
         .with_window_icon(window_icon)
-        .with_transparent(false);
+        .with_transparent(app.transparent());
+
+    let initial_size_points = app.initial_window_size();
 
     if let Some(window_settings) = &window_settings {
         window_builder = window_settings.initialize_size(window_builder);
@@ -149,14 +149,7 @@ pub fn run(mut app: Box<dyn epi::App>) -> ! {
     let window_settings = deserialize_window_settings(&storage);
     let event_loop = glutin::event_loop::EventLoop::with_user_event();
     let icon = load_icon(app.icon_data());
-    let display = create_display(
-        app.name(),
-        app.initial_window_size(),
-        window_settings,
-        app.is_resizable(),
-        icon,
-        &event_loop,
-    );
+    let display = create_display(&*app, window_settings, icon, &event_loop);
 
     let repaint_signal = std::sync::Arc::new(GliumRepaintSignal(std::sync::Mutex::new(
         event_loop.create_proxy(),