Following the idea from the "OpenScad Polygon Generator" by "PieterBos" http://www.thingiverse.com/thing:9290
But then working for any OS, any browser, without fuss. You don't even need to install anything! (might even work in mobile browsers)
Online version can be found at:
Latest sources can be found at:
How does it work? Well, simply paste the OpenSCAD code containing polygons in the lower left text area. And the polygons will show up. Then use the edit/add/delete tools to modify the polygons and it will update the code automatically (like magic). Just copy it back to OpenSCAD for the final result.
I've tested it in firefox, IE and chrome. Which all worked without a hitch.
You can use the uploaded HTML file as offline tool.