If I load an xlsx file that already has a filter, and then save the file using GemBox, it seems to throw my filtering cell away. Does GemBox support filtering at all? I know I can load the file in preserved mode but my intention is to create the filter in my C# app.
EDIT 2015-06-15:
The newer version of GemBox.Spreadsheet (version 3.9) does have an API support for filters, see the version history page. Also, you can find here an Excel AutoFilter example.
ORIGINAL ANSWER:
Unfortunately, in the current version (3.5) GemBox.Spreadsheet supports filtering only through preservation.