[#3060] - missing frames in XLS export

When exporting report to XLS via JasperServer 5.1.0 on Linux (e.g. via web interace Export > As Excel in the opened report...), cell borders/frames (if any defined e.g. via iReport > Padding And Borders), are not present in the output. I saw this problem also in JasperServer 4.5.0 when sending XLS reports via e-mail. In ODS format borders are and were OK. I am opening all formats (XLS, ODS, XLSX, ...) in LibreOffice 4.0.0.3.