Function unpin 

pub(crate) fn unpin(
    qt: &CxxQtThread<Sioul>,
    shared: &Arc<Shared>,
    uid: &str,
) -> String

“Let the plan place it”: the task’s blocks not begun deleted after ten seconds (“Undo” keeps them), one under way ending now; its link to its block, and a time given by a drag before blocks, taken out at once, put back by “Undo”. Returns what went wrong, else “”.