insertBefore
Inserts a new item just before the item pointed to by @iter.
Return
an iterator pointing to the new item
Since
2.14
Parameters
iter
a #GSequenceIter
data
the data for the new item
Inserts a new item just before the item pointed to by @iter.
an iterator pointing to the new item
2.14
a #GSequenceIter
the data for the new item