Fix flickering for Context::create_viewport_sync but now will return a Option<T>

crates/eframe/src/native/run.rs

@@ -1096,10 +1096,8 @@ mod glow_integration {
                                         .and_then(|w| w.read().window.clone())
                                 },
                             );
-                            return;
                         }
                     }
-                    render(&egui_ctx);
                 },
             );
 
@@ -2071,10 +2069,8 @@ mod wgpu_integration {
                                 *focused.read(),
                                 |id| _windows.read().get(&id).and_then(|w| w.0.clone()),
                             );
-                            return;
                         }
                     }
-                    render(&egui_ctx);
                 },
             );
 

crates/egui/src/containers/window.rs

@@ -615,10 +615,10 @@ impl<'open> Window<'open> {
                         ctx.request_repaint_viewport(ctx.get_parent_viewport_id());
                     }
 
-                    Some(InnerResponse {
+                    InnerResponse {
                         inner: content_inner,
                         response: full_response,
-                    })
+                    }
                 });
             }
         }

crates/egui/src/context.rs

@@ -2289,7 +2289,7 @@ impl Context {
         &self,
         viewport_builder: ViewportBuilder,
         func: impl FnOnce(&Context) -> T,
-    ) -> T {
+    ) -> Option<T> {
         if !self.force_embedding() {
             let mut viewport_id = ViewportId::MAIN;
             let mut parent_viewport_id = ViewportId::MAIN;
@@ -2326,9 +2326,9 @@ impl Context {
                 );
             }
 
-            out.unwrap()
+            out
         } else {
-            func(self)
+            Some(func(self))
         }
     }
 }