(in 2.5.6-rc2) empty datetime is set to present when editing

phpMyAdmin 2.5.5-pl1
MySQL 4.0.16-Max

I have a table containing a datetime field, which is set
to NULL by default. When I edit a record, whose
datetime field has not been set so far (it is still NULL),
the input-field for that datetime field in the HTML form
contains the present date and time by default (although
it should be empty). Therefore, unmindfully saving the
record (without deleting the "default" value) sets the
datetime field to the present date and time ...

Regards,
trinita
mail@trinita.de