D23088: KWindowSystem: add setNewStartupId(QWindow *...) overload

[Nicolas Fella]

nicolasfella added a reviewer: zzag.

REPOSITORY
  R278 KWindowSystem

REVISION DETAIL
  https://phabricator.kde.org/D23088

To: dfaure, broulik, davidedmundson, zzag
Cc: kde-frameworks-devel, LeGast00n, michaelh, ngraham, bruns