if (!mFrame)
if (!mDOMNode) { mAccessible = nsnull;
PRBool nsFrameTreeWalker::GetNextSibling(){  //printf("Get next\n");  if (!mFrame)    return PR_FALSE;  // get next sibling  nsIFrame* next = nsnull;  mFrame->GetNextSibling(&next);    // if failed  if (!next)  {    // if parent has content    nsIFrame* parent = nsnull;    mFrame->GetParent(&parent);        // if no parent fail    if (!parent) {      mFrame = nsnull;      return PR_FALSE;    }    // fail if we reach a parent that is accessible    mFrame = parent;    mDepth--;    if (mDepth == mDepthToFind)    {      if (IsSameContent())        return PR_TRUE;      else {        mFrame = nsnull;        return PR_FALSE;      }    } else {      // next on parent      mFrame = parent;      return GetNextSibling();    }  }  mFrame = next;  // if next has content  if (mDepth == mDepthToFind)  {    if (IsSameContent())      return PR_TRUE;    else {      mFrame = nsnull;      return PR_FALSE;    }  }    // if next doesn't have node  // call first on next  mFrame = next;  if (GetFirstChild())     return PR_TRUE;  // call next on next  mFrame = next;  return GetNextSibling();}