mPresShell->EndObservingDocument();
PrintObject::~PrintObject(){  if (mPresContext) {    mPresContext->SetImageAnimationMode(mImgAnimationMode);  }  for (PRInt32 i=0;i<mKids.Count();i++) {    PrintObject* po = (PrintObject*)mKids[i];    NS_ASSERTION(po, "PrintObject can't be null!");    delete po;  }  if (mPresShell && !mSharedPresShell) {    mPresShell->Destroy();  }  if (mDocTitle) nsMemory::Free(mDocTitle);  if (mDocURL) nsMemory::Free(mDocURL);}