diff -r c89fc366bebd -r 0ffb41625592 dialogs/SFCStepDialog.py
--- a/dialogs/SFCStepDialog.py	Thu Sep 02 21:36:29 2021 +0200
+++ b/dialogs/SFCStepDialog.py	Thu Sep 02 22:18:14 2021 +0200
@@ -57,16 +57,16 @@
 
         # Create label for SFC step name
         name_label = wx.StaticText(self, label=_('Name:'))
-        self.LeftGridSizer.AddWindow(name_label, flag=wx.GROW)
+        self.LeftGridSizer.Add(name_label, flag=wx.GROW)
 
         # Create text control for defining SFC step name
         self.StepName = wx.TextCtrl(self)
         self.Bind(wx.EVT_TEXT, self.OnNameChanged, self.StepName)
-        self.LeftGridSizer.AddWindow(self.StepName, flag=wx.GROW)
+        self.LeftGridSizer.Add(self.StepName, flag=wx.GROW)
 
         # Create label for SFC step connectors
         connectors_label = wx.StaticText(self, label=_('Connectors:'))
-        self.LeftGridSizer.AddWindow(connectors_label, flag=wx.GROW)
+        self.LeftGridSizer.Add(connectors_label, flag=wx.GROW)
 
         # Create check boxes for defining connectors available on SFC step
         self.ConnectorsCheckBox = {}
@@ -77,15 +77,15 @@
             if name == "output" or (name == "input" and not initial):
                 check_box.SetValue(True)
             self.Bind(wx.EVT_CHECKBOX, self.OnConnectorsChanged, check_box)
-            self.LeftGridSizer.AddWindow(check_box, flag=wx.GROW)
+            self.LeftGridSizer.Add(check_box, flag=wx.GROW)
             self.ConnectorsCheckBox[name] = check_box
 
         # Add preview panel and associated label to sizers
-        self.RightGridSizer.AddWindow(self.PreviewLabel, flag=wx.GROW)
-        self.RightGridSizer.AddWindow(self.Preview, flag=wx.GROW)
+        self.RightGridSizer.Add(self.PreviewLabel, flag=wx.GROW)
+        self.RightGridSizer.Add(self.Preview, flag=wx.GROW)
 
         # Add buttons sizer to sizers
-        self.MainSizer.AddSizer(
+        self.MainSizer.Add(
             self.ButtonSizer, border=20,
             flag=wx.ALIGN_RIGHT | wx.BOTTOM | wx.LEFT | wx.RIGHT)