When user click the Isosurface plugin when there is no images loaded, ExtApp
generates a crash, several lines can be added to avoid this bug:
void QmitkIsoSurface::ImageSelected(const mitk::DataTreeNode* item)
{
// nothing selected (NULL selection)
if( item == NULL || item->GetData() == NULL )
return;
if( item->GetData()->GetSource() == NULL )
{
return;
}
m_MitkImage = dynamic_cast<mitk::Image*> (item->GetData());
}