since the item takes ownership of its widget, get rid of it when it changes

svn path=/trunk/KDE/kdelibs/; revision=1185267

extenders/extenderitem.cpp

@@ -301,6 +301,7 @@ void ExtenderItem::setWidget(QGraphicsItem *widget)
     if (d->widget) {
         d->widget->removeSceneEventFilter(this);
         d->layout->removeItem(d->widget);
+        d->widget->deleteLater();
     }
 
     if (!widget || !widget->isWidget()) {

extenders/extenderitem.h

@@ -108,6 +108,7 @@ class PLASMA_EXPORT ExtenderItem : public QGraphicsWidget
 
         /**
          * @param widget The widget that should be wrapped into the extender item.
+         *               It has to be a QGraphicsWidget.
          */
         void setWidget(QGraphicsItem *widget);