We will take this opportynity to remove various QStyle specializations
from the public API in Qt5. This gives us much more freedom, for
example changing the inheritance hierarchy and even merging style
implementations (XP & Vista) later on, without worrying about BC.
=> Use QStyleFactory and/or QProxyStyle instead of creating an instance
or inheriting QWindowsVistaStyle directly.
Change-Id: I8b320036e241e877fc9bb5f4084cc6e63756cbc4
Reviewed-by: Jan Arve Sæther <jan-arve.saether@digia.com>
537efea52b