quote from:
http://techblog.willshouse.com/2013/11/01/rightzoom-and-cinch-on-osx-10-9-mavericks/
Next, to fix RightZoom and Cinch on OSX 10.9 Mavericks you need to open System Preferences and go to Security and Privacy and then choose the Accessibility tab.
「設定」> 隱私 > 點選左側「輔助使用」> 勾選 right zoom
如果沒看到right zoom，將 right zoom 拖到「輔助使用」的右側。
若再不行，開啟 rightzoom 的選項，選： activate。
If you don’t see RightZoom.app listed, find it (probably in your Applications folder) and drag it to the list of apps. Make sure it has a check mark next to it.