Just a point to remember, if you upgrade to Qt4.3, there is better support for MDI using QMdiArea which I believe is a replacement for QWorkspace.

Example :

Qt Code:
  1. m_pworkspace = new QMdiArea;
  2. m_pCanView = new CanView( this );
  3. m_pworkspace->addSubWindow( m_pCanView );
  4. m_pCanView->show();
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Regards,
Steve