whitespace-mode feature request

[John J Foerch]

Hello,

My feature request is for whitespace-mode to be configurable so the
whitespace errors buffer is less obtrusive.  There is currently a
variable called `whitespace-silent' which can disable the whitespace
errors buffer altogether.  However, other options would be nice.
One possible way would be for it to create a small, new window, which
disappears after a keystroke or a given amount of time.  BBDB has a
feature like this.

Thank you,
John Foerch