Display (Player 1) or (Player 2) consistently

src/window/vip/registers.rs

@@ -630,13 +630,13 @@ fn read_address<T: MemoryValue>(registers: &MemoryRef, address: usize) -> T {
 }
 
 impl AppWindow for RegisterWindow {
-    fn sim_id(&self) -> SimId {
-        self.sim_id
+    fn sim_id(&self) -> Option<SimId> {
+        Some(self.sim_id)
     }
 
     fn initial_viewport(&self) -> ViewportBuilder {
         ViewportBuilder::default()
-            .with_title(format!("Registers ({})", self.sim_id))
+            .with_title("Registers")
             .with_inner_size((800.0, 480.0))
     }