GelSheet is not ready yet. It doesn't work correctly on IE and may have lots of bugs. The fact that it was enabled in 1.5 was a bug.
You can enable it again if you want by editing file 'public/assets/javascript/og/FileManager.js' line 339 and change from:
}}/*,
{text: lang('spreadsheet') + ' (ALPHA)', iconCls: 'ico-sprd', handler: function() {
var url = og.getUrl('files', 'add_spreadsheet');
og.openLink(url);
}}*/
to:
}},
{text: lang('spreadsheet') + ' (ALPHA)', iconCls: 'ico-sprd', handler: function() {
var url = og.getUrl('files', 'add_spreadsheet');
og.openLink(url);
}}
and also on file 'public/assets/javascript/og/QuickAdd.js' line 43 from:
// {id: 'quick-spreadsheet', text: lang('spreadsheet'), iconCls: 'ico-sprd', handler: function() {
// var url = og.getUrl('files', 'add_spreadsheet');
// og.openLink(url/*, {caller: 'documents-panel'}*/);
// }},
to:
{id: 'quick-spreadsheet', text: lang('spreadsheet'), iconCls: 'ico-sprd', handler: function() {
var url = og.getUrl('files', 'add_spreadsheet');
og.openLink(url/*, {caller: 'documents-panel'}*/);
}},
All of your data is safe, don't worry.