comctl32: tweak node initialization

[Rafał Mużyło]

To make things clear, this patch isn't really correct.
This comes from bug 43998, where it's described what's exactly wrong
with it.
Yet, bugzilla bugs have much worse visibility than wine-devel.
So, if someone, who understands the initialization order in treeview,
could shed some light on this problem, that should get this patch
moving in the correct direction.

- how is treeview initialized ?
- when can this initialization go wrong the way it does in bug 43998 ?
- what would be the proper place for this call (cause doing it *during* painting is most likely wrong) ?