fixed the splitoverlay not disappearing when the window is not selected

src/widgets/helper/splitoverlay.hpp

@@ -19,6 +19,7 @@ public:
 protected:
     void paintEvent(QPaintEvent *event) override;
     void resizeEvent(QResizeEvent *event) override;
+    void mouseMoveEvent(QMouseEvent *event) override;
 
 private:
     // fourtf: !!! preserve the order of left, up, right and down