(size_trunc_len): support automatic maximum unit for specified size.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Calrify widget redraw in runtime.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
(overwrite_query_dialog): adjust dialog size.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>