void DialogRepositionSurface::OnUndo( )
{
  LayerSurface* surf = (LayerSurface*)MainWindow::GetMainWindow()->GetActiveLayer( "Surface" );
  if ( surf )
  {
    surf->Undo();
    UpdateUI();
  }
}
void DialogRepositionSurface::OnUndo( wxCommandEvent& event )
{
  LayerSurface* surf = (LayerSurface*)MainWindow::GetMainWindowPointer()->GetActiveLayer( "Surface" );
  if ( surf )
  {
    surf->Undo();
    UpdateUI();
  }
}