Easynth has released version 2.67 of its ForeUI prototyping tool (http://www.foreui.com/). The upgrade allows you to add a comment on any entity in the action editor.

ForeUI is a tool to create static or interactive prototypes for websites/software in your mind. Your prototype will be skinnable, and you can change its style from “hand drawing” to “wire frame,” 
and to native OS styles. The behavior of prototypes can be defined with flow charts to handle specific events.

The prototype can be exported to wireframe images, PDF documents or DHTML simulation. The created prototypes will be useful for idea sharing, design review, feedback collection or usability testing etc.

ForeUI requires Mac OS X 10.5 or higher. It’s Universal Binary so runs natively on both PowerPC and Intel Macs. The cost is US$99 per user for a lifetime usage license.