Getting wrong name in mouse hover property in Qt

Question

I am having QGraphicsScene which contains many digital gates ( AND,OR,NOR etc ) which are made up of Arc, Polyline, Circle, Straight line etc.
I am implementing a feature like, when I hover mouse over input of Gates, it's name should be seen on tool tip.

In above screen shot, there is a gate (i2) which has 2 inputs ( top input line is a[2] and bottom input line is a[3] )
When I hover inside Red line, I get a[3] as hovering name on cursor tool tip.
And when I hover outside Red line and inside of Blue line, I get a[2] as hovering name on cursor tool tip.

But I am expecting, hovering info will be visible only when I hover on input lines of gates. Why am I getting input line names when I hover around input lines ? And moreover, above hovering info is also wrong.

Here is my code :

bool myViewer::eventFilter(QObject* watched, QEvent* event)
{
  case QEvent::MouseMove:
   {
      QMouseEvent* mouseEvent = static_cast<QMouseEvent*>(event);
      QPointF mousePoint = _view->mapToScene(mouseEvent->pos());
      QGraphicsItem* SelectedItem = scene->itemAt(mousePoint, QTransform());
      if(SelectedItem)
      {
          myPoly* item = qgraphicsitem_cast<myPoly*>(SelectedItem);
          if(item)
          {
              item->setToolTip(item->GetPolyLineName()); // GetPolyLineName gives name as a[2] or a[3]
          }
      }
   }
    break;
 }

myPoly.h

 class myPoly : public QGraphicsPathItem {    
      public:
           QString &GetPolyLineName();  
   }