When use open one 3D image, and open "interactive segmentation plugin", choose the image, click on "Thresholding" button, it will let user move the threshold slider, when user choose one threshold value and then click "OK" button, the crash occurs due to running in

void QmitkBinaryThresholdToolGUI::OnAcceptThresholdPreview()
{

if (m_BinaryThresholdTool.IsNotNull())
{
  QmitkNewSegmentationDialog* dialog = new QmitkNewSegmentationDialog( this ); // needs a QWidget as parent, "this" is not QWidget
  dialog->setPrompt("What did you just segment?");  //<-- this line 
  ...
}

}

then it call

void QmitkNewSegmentationDialog::setPrompt( const QString& prompt )
{

lblPrompt->setText( prompt );

}

where lblPrompt is not initialized, according to the new definitons, the line can be commented out.