Excel UI should propagate time stamps consistently

[JS3xton]

It would be nice if the Excel UI propagated time stamps more consistently. Currently, I lazily copy and paste any columns from my input Excel sheet which have time stamp data to the output sheet because the output sheet doesn't preserve the formatting.

[castillohair]

I've seen that problem too: an output file from FlowCal has floating-point numbers instead of proper datetime values when it copies dates/times from an input excel file.

If I read the output file from python, I can do the following to recover a proper datetime:

datetime.datetime(1899, 12, 30) + datetime.timedelta(days=time)

where time is any value from an improperly formatted time column.

Obviously this is not a real solution, and having pandas not mess up the formatting would be better.