Function write_gaps 

fn write_gaps(
    qt: &CxxQtThread<Sioul>,
    shared: &Arc<Shared>,
    uid: &str,
    edit: &TaskEdit,
)

The waits the form gave a gap (TaskEdit::wait_gaps), written in the tasks waited for, as sioul tasks import writes them (tasks::set_gap): once the task that waits is written. What fails is said in the status line; the task itself is kept.