new feature: pause playback when GUI window is closed

src/gui/draw.rs

@@ -48,10 +48,15 @@ impl SoundpadGui {
                 &mut self.config.save_scale_factor,
                 "Always remember UI scale factor",
             );
+            let pause_on_exit_response = ui.checkbox(
+                &mut self.config.pause_on_exit,
+                "Pause audio playback when the window is closed",
+            );
 
             if save_volume_response.changed()
                 || save_input_response.changed()
                 || save_scale_response.changed()
+                || pause_on_exit_response.changed()
             {
                 self.config.save_to_file().ok();
             }

src/gui/mod.rs

@@ -149,7 +149,13 @@ pub async fn run() -> Result<(), Box<dyn Error>> {
             Ok(Box::new(SoundpadGui::new(&cc.egui_ctx)))
         }),
     ) {
-        Ok(_) => Ok(()),
+        Ok(_) => {
+            let config = get_gui_config();
+            if config.pause_on_exit {
+                make_request_sync(Request::pause()).ok();
+            }
+            Ok(())
+        }
         Err(e) => Err(e.into()),
     }
 }