FEM: constraint body heat source vp, fix tree view icon

src/Mod/Fem/femguiobjects/ViewProviderFemConstraint.py

@@ -46,6 +46,7 @@ class ViewProxy(object):
         vobj.Proxy = self
 
     # needs to be overwritten, if no standard icon name is used
+    # see constraint body heat source as an example
     def getIcon(self):
         """after load from FCStd file, self.icon does not exist, return constant path instead"""
         # https://forum.freecadweb.org/viewtopic.php?f=18&t=44009

src/Mod/Fem/femguiobjects/_ViewProviderFemConstraintBodyHeatSource.py

@@ -1,5 +1,6 @@
 # ***************************************************************************
 # *   Copyright (c) 2017 Markus Hovorka <m.hovorka@live.de>                 *
+# *   Copyright (c) 2020 Bernd Hahnebach <bernd@bimstatik.org>              *
 # *                                                                         *
 # *   This file is part of the FreeCAD CAx development system.              *
 # *                                                                         *
@@ -33,6 +34,7 @@ from . import ViewProviderFemConstraint
 
 class ViewProxy(ViewProviderFemConstraint.ViewProxy):
 
-    pass
+    def getIcon(self):
+        return ":/icons/FEM_ConstraintHeatflux.svg"  # the heatflux icon is used
 
 ##  @}