(eframe) add Frame.set_visible (#1808)

eframe/src/native/epi_integration.rs

@@ -120,6 +120,7 @@ pub fn handle_app_output(
         decorated,
         drag_window,
         window_pos,
+        visible,
     } = app_output;
 
     if let Some(decorated) = decorated {
@@ -150,6 +151,10 @@ pub fn handle_app_output(
     if drag_window {
         let _ = window.drag_window();
     }
+
+    if let Some(visible) = visible {
+        window.set_visible(visible);
+    }
 }
 
 // ----------------------------------------------------------------------------