Description:
The style editor has a browse button for selecting a font background image.
Should use Gowri's new image picker customizer.  Looks like it's using the old
Reef one.

Evaluation:
This is a good RFE. 

Unfortunately, the image editor is a custom editor for URL property of image. It
is tightly bound to the image URL property editor. So Style builder can not use
it directly. The soultion is to create a common utility class for adding images
to project and share that between different areas such as CSS editor, style
builder and image URL property editor etc.

Lets visit this for Mako.