FEM: Python base object fix regression added with 71c9694824 by readding getstate method

src/Mod/Fem/femguiobjects/ViewProviderFemConstraint.py

@@ -55,8 +55,8 @@ class ViewProxy(object):
     def attach(self, vobj):
         default = coin.SoGroup()
         vobj.addDisplayMode(default, "Default")
-        # self.Object = vobj.Object
-        # self.ViewObject = vobj
+        self.Object = vobj.Object  # used on various places, claim childreens, get icon, etc.
+        # self.ViewObject = vobj  # not used ATM
 
     def getDisplayModes(self, obj):
         "Return a list of display modes."
@@ -104,7 +104,9 @@ class ViewProxy(object):
             FreeCAD.Console.PrintError(message + "\n")
         return True
 
-    # a few objects had this method in their class before the move to this base class
-    # these objects will give a setAttr failed error on document loading without this method
+    # they are needed, see https://forum.freecadweb.org/viewtopic.php?f=18&t=44021
+    def __getstate__(self):
+        return None
+
     def __setstate__(self, state):
         return None

src/Mod/Fem/femguiobjects/_ViewProviderFemResultMechanical.py

@@ -33,7 +33,6 @@ __url__ = "http://www.freecadweb.org"
 import matplotlib.pyplot as plt
 import numpy as np
 
-from pivy import coin
 from PySide import QtCore
 from PySide import QtGui
 from PySide.QtCore import Qt
@@ -51,12 +50,6 @@ class _ViewProviderFemResultMechanical(ViewProviderFemConstraint.ViewProxy):
     A View Provider for the FemResultObject Python derived FemResult class
     """
 
-    def attach(self, vobj):
-        default = coin.SoGroup()
-        vobj.addDisplayMode(default, "Default")
-        self.Object = vobj.Object
-        self.ViewObject = vobj
-
     def setEdit(self, vobj, mode=0):
         ViewProviderFemConstraint.ViewProxy.setEdit(
             self,
@@ -85,12 +78,6 @@ class _ViewProviderFemResultMechanical(ViewProviderFemConstraint.ViewProxy):
                 FreeCAD.Console.PrintError("Error in onDelete: {0} \n".format(err))
         return True
 
-    def __getstate__(self):
-        return None
-
-    def __setstate__(self, data):
-        return None
-
 
 class _TaskPanel:
     """