Revert "Disable theming of menu bar."
This reverts commit 7b8cd427 . This basically makes creator looks uglier on most platforms while not really fixing anything on Ubuntu. The menubar is on ubuntu (and mac) not shown in natively compiled versions so it effectively fixes nothing, but makes the appearance inconsistent on other platforms. Change-Id: I4576b4dcc722dca59a7480eba41ce8efa970533b Reviewed-by: Eike Ziller <firstname.lastname@example.org>