All I really want to know is whether a worksheet is hidden or not.  It would be
nice if there was a simple boolean method on HSSFSheet that showed this
attribute. It would be so simple to do.  But the way Workbook hides the
boundsheets ArrayList, this is just not possible.  It seems like the only thing
that Workbook doesn't report about any given BoundsheetRecord is the option flag.

Here's what I propose for HSSFWorkbook:

  /**
   * Returns true if given worksheet is hidden.
   *
   * @param  iSheetnum index of worksheet to test.
   * @return true if given worksheet is hidden.
   * @throws    IndexOutOfBoundsException if iSheetnum is out of range 
   */
  public boolean isHidden( int iSheetnum )
  {
    getWorkbook().isHidden( iSheetnum );
  }

Then in Workbook:
  /**
   * Returns true if given worksheet is hidden.
   *
   * @param  iSheetnum index of worksheet to test.
   * @return true if given worksheet is hidden.
   * @throws    IndexOutOfBoundsException if iSheetnum is out of range 
   */
  public boolean isHidden( int iSheetnum )
  {
    BoundSheetRecord bsr = getBoundsheetRecord( iSheetnum );
    return bsr.getOptions() != 0;
  }
    
  /**
   * Returns the BoundsheetRecord associated with given sheet number.
   *
   * @param  iSheetnum index of BoundsheetRecord to return.
   * @return the BoundsheetRecord at the specified position in this list.
   * @throws    IndexOutOfBoundsException if iSheetnum is out of range 
   *        <tt>(iSheetnum &lt; 0 || iSheetnum &gt;= boundsheets.size())</tt>.
   */
  protected BoundsheetRecord getBoundsheetRecord( int iSheetnum )
  { 
    return (BoundsheetRecord)boundsheets.get( iSheetnum );
  }