Squashed commit of the following:

commit febd3dfe9eae3b45b60c0c4e33d77bfb200e679c
Author: Moriyoshi Koizumi <mozo@mozo.jp>
Date:   Fri Jul 26 20:32:14 2013 +0900

    Update example.

commit 2f271064b46aa43ec93ae03944983a5138df5793
Author: Moriyoshi Koizumi <mozo@mozo.jp>
Date:   Wed Jul 17 10:51:56 2013 +0900

    Mouse wheel event support.