[fix] align remote mouse coordinates with the displayed video area

apps/desktop/src/gui/rendering/slint_video_presenter.h

@@ -28,7 +28,6 @@ public:
   struct SurfaceState {
     std::string selected_stream;
     bool fullscreen = false;
-    size_t tab_count = 0;
   };
 
   struct Frame {
@@ -78,4 +77,4 @@ private:
 
 }  // namespace crossdesk
 
-#endif
+#endif