Zoho Sheets

I was working in Zoho sheets. There is a provision for uploading the spread sheets. When I tried uploading a spreadsheet, I found that I was able to select files of any types like docs, txts, gifs etc., Though uploading such files is restricted, it should not allow me to select such files in the first instance itself. My suggestion is that just allow to select only files of type xls and csvs rather restricting while we upload.
sudhakarrathinam