An entry cannot change between a separator and an ordinary entry; that is,
it is not possible to set a non-null label on an entry that has a null
label (separators), or to set a null label to an entry that has a non-null
label. The function will silently fail if that happens.
Sets the label of an entry.
An entry cannot change between a separator and an ordinary entry; that is, it is not possible to set a non-null label on an entry that has a null label (separators), or to set a null label to an entry that has a non-null label. The function will silently fail if that happens.