Hello

I would like to sort my plot legend alphabetically. Therefore I imlemented following class inheriting from QwtLegend assuming that the virtual legendItems(void) method is called by the plot.
Qt Code: 
  1. class Legend : public QwtLegend
  2. {
  3.    public:
  4.       Legend(QWidget* pParent = 0) : QwtLegend(pParent)
  5.       {   
  6.       }
  7.  
  8.       QList<QWidget*> legendItems(void) const
  9.       {
  10.          QList<QWidget*> lLegendItems = QwtLegend::legendItems();
  11.          qSort(lLegendItems.begin(), lLegendItems.end(), Legend::lessThan);
  12.          return lLegendItems;
  13.       }
  14.  
  15.       static bool lessThan(QWidget* pLi1, QWidget* pLi2)
  16.       {
  17.          if(pLi1 && pLi2)
  18.          {
  19.             if (pLi1->inherits("QwtLegendItem") && pLi2->inherits("QwtLegendItem"))
  20.             {
  21.                QwtLegendItem* lLabel1 = (QwtLegendItem*)pLi1;
  22.                QwtLegendItem* lLabel2 = (QwtLegendItem*)pLi2;
  23.                return lLabel1->text().text().toLower() < lLabel2->text().text().toLower();
  24.             }
  25.          }
  26.          return false;
  27.       }
  28. };
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The legend is added to the plot...
Qt Code: 
  1. Legend* lLegend = new Legend(mPlot->canvas());
  2. // some initialisations...
  3. mPlot->insertLegend(lLegend, QwtPlot::ExternalLegend);
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But the legendItems(void) method is never called.
Any idea what's wrong?

Best Regards
Stefan