Can't set backgrond color to excel 2007 file format

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Use excel 2007 to new an empty xlsx.
2. try to set the background color of A1 to red

What is the expected output? What do you see instead?
expected:background color of cell A1 is red.        
result:org.zkoss.zss.model.impl.XSSFBookImpl cannot be cast to 
org.apache.poi.hssf.usermodel.HSSFWorkbook

What version of the product are you using? On what operating system?
11/3, FF

Please provide any additional information below.
If the file is based on excel 97~2003, no such issue.

Original issue reported on code.google.com by whkuoatt...@gmail.com on 5 Nov 2010 at 2:46

[GoogleCodeExporter]

Original comment by chenhe...@gmail.com on 22 Nov 2010 at 11:58

• Changed title: Can't set backgrond color to excel 2007 file format
• Changed state: Fixed