Something I had wanted to figure out. The LandscapeMapEditor on wondefl provided all that was required to get started. The original code was under a MIT license and that license is therefore carried on.
This is a strictly actionscript project. Label and InputText controls come from the minimalComps library by Keith Peters.
NOTE. It looks like I changed the controls for the diameter of the circle. Use the up arrow and down arrow to increase/decrease the radius of the circle.