FormDesigner - a basic form designer you can incorporate into your programs
PropEd - a companion property editor
Please note that the FormDesigner has been developed and tested on MacOS. I do have some Windows specific code in some places where necessary but I have not really tested that. The biggest thing being canvas transparency. Also, some stuff like bringing an object to the front, simply will not work on Windows.
Consider these modules to be very much alpha as they are not feature complete and subject to change so use at your own risk. Both modules have examples embedded into them. The FormDesigner shows how to use the the property editor with it. One major feature still missing is code generation so you can't do a whole lot with it yet except play with it.
So everything is still kinda crude but you may be able to use it as a basis for your own GUI Designer.
Bugs? Most definitely.

I just wanted to get this out early to see how much interest there is in this.
Download here: https://filedn.com/lHJwd7m6TKKuPoeDaPqWKjJ
Thanks!
Phil