I needed to change the background color of the text region of a flash combobox - using AS3 at runtime.
Styles for some reason were not working. The solution was to directly address the textfield property and change its background color. Here's an example:
cbo.textField.textField.background = true;
cbo.textField.textField.backgroundColor = 0xDEDE29;
Just created my new sig using Google's QR code API ( http://createqrcode.appspot.com/ ). It creates the codes with error correction (there are some settings that you can use to modify this), so its possible to actually delete a part of it and enter your own image/text in the middle of the QR code.
I had to play around a little with my name in the middle. If it is not aligned properly on the QR code or if it covers the wrong area, the code won't be recognized.