diff --git a/src/Mod/OpenSCAD/OpenSCADCommands.py b/src/Mod/OpenSCAD/OpenSCADCommands.py
index 93b9f8d92e..5d85395d06 100644
--- a/src/Mod/OpenSCAD/OpenSCADCommands.py
+++ b/src/Mod/OpenSCAD/OpenSCADCommands.py
@@ -199,6 +199,8 @@ class AddSCADTask:
             FreeCAD.Console.PrintError(unicode(translate('OpenSCAD','Running OpenSCAD failed'))+u'\n')
 
 class AddOpenSCADElement:
+    def IsActive(self):
+        return not FreeCADGui.Control.activeDialog()
     def Activated(self):
         panel = AddSCADTask()
         FreeCADGui.Control.showDialog(panel)
diff --git a/src/Mod/OpenSCAD/importCSG.py b/src/Mod/OpenSCAD/importCSG.py
index d6c34ceb6c..39b520c5a9 100644
--- a/src/Mod/OpenSCAD/importCSG.py
+++ b/src/Mod/OpenSCAD/importCSG.py
@@ -539,7 +539,10 @@ def p_linear_extrude_with_twist(p):
     print "Linear Extrude With Twist"
     h = float(p[3]['height'])
     print "Twist : ",p[3]
-    t = float(p[3]['twist'])
+    if 'twist' in p[3]:
+        t = float(p[3]['twist'])
+    else:
+        t = 0
     if (len(p[6]) > 1) :
         obj = fuse(p[6],"Linear Extrude Union")
     else :
@@ -862,7 +865,7 @@ def p_square_action(p) :
     mysquare = doc.addObject('Part::Plane',p[1])
     mysquare.Length=x
     mysquare.Width=y
-    if p[9]=='true' :
+    if p[3]['center']=='true' :
        center(mysquare,x,y,0)
     p[0] = [mysquare]
 
diff --git a/src/Mod/OpenSCAD/replaceobj.py b/src/Mod/OpenSCAD/replaceobj.py
index 54185734c2..f5e50fedf7 100644
--- a/src/Mod/OpenSCAD/replaceobj.py
+++ b/src/Mod/OpenSCAD/replaceobj.py
@@ -11,14 +11,15 @@ def replaceobj(parent,oldchild,newchild):
                 setattr(parent,propname,newchild)
                 print propname, parent.getPropertyByName(propname)
             #else: print propname,propvalue
+    parent.touch()
 
 def replaceobjfromselection(objs):
     assert(len(objs)==3)
-    if objs[0] in objs[1].InList: parent, oldchild, newchild = objs
+    if objs[2] in objs[0].InList: oldchild, newchild, parent = objs
+    elif objs[0] in objs[1].InList: parent, oldchild, newchild = objs
     elif objs[0] in objs[2].InList: parent, newchild, oldchild = objs
     elif objs[1] in objs[0].InList: oldchild, parent, newchild = objs
     elif objs[1] in objs[2].InList: newchild, parent, oldchild = objs
-    elif objs[2] in objs[0].InList: oldchild, newchild, parent = objs
     elif objs[2] in objs[1].InList: newchild, oldchild, parent = objs
     else: assert(False)
     replaceobj(parent,oldchild,newchild)