Add command to retrieve window size

winit/src/application.rs

@@ -3,6 +3,7 @@
 mod profiler;
 mod state;
 
+use iced_graphics::core::window::SizeType;
 pub use state::State;
 
 use crate::conversion;
@@ -747,6 +748,21 @@ pub fn run_command<A, E>(
                         height,
                     });
                 }
+                window::Action::FetchSize {
+                    size_type,
+                    callback,
+                } => {
+                    let width_height = match size_type {
+                        SizeType::Inner => window.inner_size(),
+                        SizeType::Outer => window.outer_size(),
+                    };
+                    let width_height =
+                        (width_height.width, width_height.height);
+
+                    proxy
+                        .send_event(callback(width_height))
+                        .expect("Send message to event loop")
+                }
                 window::Action::Maximize(maximized) => {
                     window.set_maximized(maximized);
                 }