wxGUI: set background color for map window (wxPython 3)

       (merge https://trac.osgeo.org/grass/changeset/64143 from trunk)


git-svn-id: https://svn.osgeo.org/grass/grass/branches/releasebranch_7_0@64144 15284696-431f-4ddb-bdfa-cd5b030d7da7

gui/wxpython/mapwin/buffered.py

@@ -74,7 +74,8 @@ class BufferedMapWindow(MapWindowBase, wx.Window):
         """
         MapWindowBase.__init__(self, parent=parent, giface=giface, Map=Map)
         wx.Window.__init__(self, parent=parent, id=id, style=style, **kwargs)
-
+        self.SetBackgroundColour("white")
+        
         self._properties = properties
 
         # flags