Delay window visibility to prevent white background on app launch (#702)

Co-authored-by: Jakub Panek <me@panekj.dev>

src/app_handle.rs

@@ -301,6 +301,7 @@ impl ApplicationHandle {
         let logical_size = size.map(|size| LogicalSize::new(size.width, size.height));
 
         let mut window_builder = floem_winit::window::WindowBuilder::new()
+            .with_visible(false)
             .with_title(title)
             .with_decorations(!undecorated)
             .with_transparent(transparent)

src/window_handle.rs

@@ -197,6 +197,9 @@ impl WindowHandle {
         }
         // Now that the renderer is initialized, draw the first frame
         self.render_frame();
+        if let Some(window) = self.window.as_ref() {
+            window.set_visible(true);
+        }
     }
 
     pub fn event(&mut self, event: Event) {