fix openxr screen freeze

src/backend/overlay.rs

@@ -150,6 +150,7 @@ pub trait OverlayRenderer {
     fn resume(&mut self, app: &mut AppState);
     fn render(&mut self, app: &mut AppState);
     fn view(&mut self) -> Option<Arc<ImageView>>;
+    fn extent(&self) -> [u32; 3];
 }
 
 pub struct FallbackRenderer;
@@ -162,6 +163,9 @@ impl OverlayRenderer for FallbackRenderer {
     fn view(&mut self) -> Option<Arc<ImageView>> {
         None
     }
+    fn extent(&self) -> [u32; 3] {
+        [0, 0, 0]
+    }
 }
 // Boilerplate and dummies
 
@@ -204,6 +208,9 @@ impl OverlayRenderer for SplitOverlayBackend {
     fn view(&mut self) -> Option<Arc<ImageView>> {
         self.renderer.view()
     }
+    fn extent(&self) -> [u32; 3] {
+        self.renderer.extent()
+    }
 }
 impl InteractionHandler for SplitOverlayBackend {
     fn on_left(&mut self, app: &mut AppState, pointer: usize) {