Alrighty, I have released GWEN. After a few weeks of implementing feature requests, fixing a few known issues, and fixing issues that people find, I will release an update to it. Please keep that in mind. All the legal stuff is written in ENGLISH in the readme, not legalese. Also keep in mind that you will need a skin file for GWEN in the same directory as your CAP. A default skin is provided in the zip file.
GWEN makes beautiful, powerful interfaces. I've already used it in a few personal projects. You won't regret your purchase. For more in depth information on GWEN, read its project page here: http://code.google.com/p/gwen/
Benefits of using GWEN over Construct UI elements: GWEN uses CONSTRUCT to render itself, not Windows, meaning it is much more flexible. All of GWEN's interface elements are created, modified, and maintained in the event sheet - meaning instead of cluttering up your layout, they can be organized into groups and minimized. GWEN can do all the measuring for you, meaning absolute coordinates aren't necessary - elements can be docked, ordered, and aligned based on relative positions rather than absolute coordinates, taking a lot of math off your shoulders and giving you flexibility, and meaning that changes at runtime (whether the user resizes something or the resolution changes) are reacted to instantaneously and smoothly. GWEN has a lot more interface options than Construct. Context Menus, toolbar ribbons, tree lists, inventory screens, etc. These are only a few of the many benefits, but they are the ones I like the most.
Video Two! (Shows off a lot more widgets than video one. The program in this video was made fairly quickly with GWEN, despite the complexity.)
I will be recording and releasing Youtube videos outlining (in great depth) how to use each widget in the coming days/weeks. I will also create a proper release thread in the completed addons forum. However, for now: