ToolBar: Get proper pressed state on Mac

Depends on https://codereview.qt-project.org/57500

Change-Id: I131fa8e25322a10a10878e5f603084e951d101ad
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>
Reviewed-by: Jens Bache-Wiig <jens.bache-wiig@digia.com>