Fix compatibility with wx3.0

Author: ggilestro

panels/default_panels.py

@@ -1393,7 +1393,7 @@ def CreateCanvas(self, size):
         else:
             self.canvas = MyWXCanvas(self.virtualw, size)
 
-        self.virtualw.SetBackgroundColour(wx.NamedColor("WHITE"))
+        self.virtualw.SetBackgroundColour(wx.NamedColour("white"))
 
         self.virtualw.SetVirtualSize(size)
         #self.virtualw.SetScrollbars(20, 20, size[0]/20, size[1]/20)