gui: fix wrong logic on update/render/deinit

The older implementation caused some elements to be
update/rendered/deinitialized more than once per call. For example,
considering the following tree of GUI elements:

A
    B
    C
        D
    E

The older implementation would update/render/deinitialize C and E more
than once, as shown below:

Update A
Update B
Update C
Update D
Update E
Update C

This was because a GUI element was acting on its siblings, but the
siblings would also act on theirs, causing the extra calls.

OTOH, as an additional improvement, no nested call is now required for
siblings.

0 files changed, 0 insertions, 0 deletions