#4318 desktop scaling was breaking pointer polling

'get_mouse_position()' is only used for sending coordinates to the server, so we have to use the 'client-to-server' coordinate scaling methods

xpra/client/gtk3/client.py

@@ -92,7 +92,7 @@ def get_mouse_position(self) -> tuple[int, int]:
         if not root:
             return -1, -1
         p = root.get_pointer()[-3:-1]
-        return self.sp(p[0] or 0, p[1] or 0)
+        return self.cp(p[0] or 0, p[1] or 0)
 
 
 GObject.type_register(XpraClient)