pub trait WindowOps {
// Required methods
fn set_fullscreen(&mut self, fullscreen: &FullscreenPlan);
fn set_decorations(&mut self, decorations: bool);
fn request_inner_size(&mut self, size: Size);
fn set_outer_position(&mut self, position: Point);
// Provided method
fn set_resizable(&mut self, _resizable: bool) { ... }
}