change white background for icons in PouInstanceVariablePanel to transparent
in wxPython 2.8 panel has white background and therefore white
background is appropriate, but in wxPython 3.0 panel has grey
background (on GNU/Linux and on Windows).
Transparent background looks good on both wxPython versions and on all platforms.
These classes are intended for use server-side.
e.g. in a django view.py :
from pyjs.jsonrpc.django import JSONService, jsonremote