#82 Delete all columns/rows cause wrong display

[Lex Sung]

<?xml version="1.0" encoding="UTF-8"?>
<zk>
<window title="" width = "100%" height = "100%">
<button label="Insert First Row">
<attribute name="onClick">
ss1.getSelectedSheet().insertRows(0,0);
</attribute>
</button>
<button label="Delete First Row">
<attribute name="onClick">
ss1.getSelectedSheet().deleteRows(0,0);
</attribute>
</button>
<spreadsheet id="ss1" url="/test2/xls/empty.xls"
width = "800px"
height = "600px"
maxrows = "1"
/>
</window>
</zk>

in this zul file,
delete first row,
the header of first row still visible.
then insert first row,
there will be a row header without any cells.

some errors will happen when trying to delete the new inserted row.