Estimated time left in progress bar?

[Petter Reinholdtsen <pere@hungry.com>]

[Denis Barbier]
> See #172218, I do not know what joeyh has in mind.  Anyway unless tausq
> objects I will apply this patch soon, so that cdebconf can be uploaded.
> Having progress bar support in the slang frontend would also be nice.

Where is the current progress bar design documented?  I am unable to
find any description.

After checking the source code, it seem to only support a simple
progress bar, with no way to display time used or estimated time left.
I believe displaying such time information is vital for users reading
the progress information.  Because of this I would like to check the
design.