diff --git a/catser/app.py b/catser/app.py
index e78267f..f2c37be 100644
--- a/catser/app.py
+++ b/catser/app.py
@@ -55,6 +55,7 @@ class CatserApp:
             on_mouse_down=self.controller.on_mouse_down,
             on_mouse_move=self.controller.on_mouse_move,
             on_mouse_up=self.controller.on_mouse_up,
+            on_display_change=self.controller.refresh_display_bounds,
         )
 
         # 4. ActivityWatch Initial Ping