desktop: Add RuffleEvent::ThemeChanged

desktop/src/app.rs

@@ -538,6 +538,10 @@ impl App {
                     return;
                 }
 
+                winit::event::Event::UserEvent(RuffleEvent::ThemeChanged(theme)) => {
+                    self.gui.borrow().set_theme(theme);
+                }
+
                 _ => (),
             }
 

desktop/src/custom_event.rs

@@ -1,6 +1,7 @@
 //! Custom event type for desktop ruffle
 
 use crate::player::LaunchOptions;
+use winit::window::Theme;
 
 /// User-defined events.
 pub enum RuffleEvent {
@@ -24,4 +25,7 @@ pub enum RuffleEvent {
 
     /// The user selected an item in the right-click context menu.
     ContextMenuItemClicked(usize),
+
+    /// System theme has changed.
+    ThemeChanged(Theme),
 }

desktop/src/gui/controller.rs

@@ -138,6 +138,14 @@ impl GuiController {
         })
     }
 
+    pub fn set_theme(&self, theme: Theme) {
+        self.egui_winit.egui_ctx().set_visuals(match theme {
+            Theme::Light => egui::Visuals::light(),
+            Theme::Dark => egui::Visuals::dark(),
+        });
+        self.window.request_redraw();
+    }
+
     pub fn descriptors(&self) -> &Arc<Descriptors> {
         &self.descriptors
     }
@@ -178,11 +186,7 @@ impl GuiController {
         }
 
         if let WindowEvent::ThemeChanged(theme) = &event {
-            let visuals = match theme {
+            self.set_theme(*theme);
-                Theme::Dark => egui::Visuals::dark(),
-                Theme::Light => egui::Visuals::light(),
-            };
-            self.egui_winit.egui_ctx().set_visuals(visuals);
         }
 
         if matches!(