Someone recently wondered how to pick a color of a pixel from the screen in as3. If you have a bitmap image you can simply grab the color value using BitmapData.getPixel(). But if you want to capture a pixel color value in the stage as the user sees it, including vector graphics, you need another technique.
The way I found was to make a 1×1 bitmap, and then drawing the stage to the bitmap using a translation matrix for the offset. The result is then in the single pixel of the bitmap.
var bmd:BitmapData = new BitmapData(1, 1, false, 0x000000);
var matrix:Matrix = new Matrix();
return bmd.getPixel(0, 0);