"OS X comes with built-in handwriting recognition technology called Inkwell (or Ink). If you connect a graphics tablet to your Mac, you can write on the tablet using a stylus, and Inkwell translates what you write to typed words in your document." Click here for more information
You may run into undesired behaviour with Painter 12 if you have enabled Handwriting recognition in Mac OS. If you've enabled handwriting recognition, you will have the following Ink panel on your screen. This Ink panel allows you to toggle write anywhere on or off. This needs to be turned off to allow interaction with Painter 12.
Write Anywhere off
You can also turn handwriting recognition on or off by going to System Preferences and opening Ink
Note: Ink will only appear in System Preferences if you have a tablet or other pen input device connected