Wordfast Pro 3 can't be opened because it is from an unidentified developer
When you attempt to run Wordfast Pro 3 in OS X, a message saying “Wordfast3.app” can't be opened because it is from an unidentified developer may stop you.
Click the Apple icon in the top left corner, select System Preferences > Security & Privacy, and click Open Anyway.
You will be able to start Wordfast Pro 3 now. But may still see a security warning saying the app was downloaded from the Internet.
Click Open and Wordfast Pro 3 will start.