Designer/Windows: Add close button to QWidget-type previews.
Designer/Windows: Add close button to QWidget-type previews.

Change-Id: I6063e921c0ccc3588fb6268be39c45a7479e991c
Reviewed-by: Friedemann Kleint <1b9f2592239daaec4856ccc1cfb4d2d55b35fb71@nokia.com>

mer-qt/qttools,mer-qt/qttools,mer-qt/qttools,mer-qt/qttools,mer-qt/qttools,mer-qt/qttools