Maybe a bug from Qt : Impossible to change the height of QToolBarExtension

[Alundra]

Hi,
Maybe a bug found in Qt, doing that the height doesn't change.

QToolBarExtension
{
  height: 19px;
}

QToolBarExtension
{
  height: 19px;
}

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Changing the background color works correctly but the height is impossible to change.
Bug from Qt or bad use ?
Thanks