cabana: cancel signal highlighting on leaveEvent (#27315)

cacnel signal hilighting on leaveEvent

tools/cabana/signaledit.cc

@@ -449,3 +449,8 @@ void SignalView::signalHovered(const Signal *sig) {
     }
   }
 }
+
+void SignalView::leaveEvent(QEvent *event) {
+  emit highlight(nullptr);
+  QWidget::leaveEvent(event);
+}

tools/cabana/signaledit.h

@@ -89,6 +89,7 @@ signals:
 
 private:
   void rowsChanged();
+  void leaveEvent(QEvent *event);
 
   QString msg_id;
   QTreeView *tree;