The date and time fields of the main tab posted undo events
for every date/timeChanged signal. Thus, when changing the
day of the month to e.g. 21, this would result in two date
change events: one to the 2nd and one to the 21st. This is
very irritating.
Instead listen to editingFinished() events, which thankfully
exist for these widgets.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>