import matplotlib
matplotlib.use('WXAgg')
import wx
from matplotlib.backends.backend_wxagg import FigureCanvasWxAgg as FigureCanvas
from matplotlib.figure import Figure
from matplotlib.backends.backend_wx import NavigationToolbar2Wx
from traits.api import Instance
from traitsui.wx.editor import Editor
from traitsui.wx.basic_editor_factory import BasicEditorFactory
ValueError: cannot set toolkit to wx because it has already been set to qt4