diff -r c89fc366bebd -r 0ffb41625592 controls/ProjectPropertiesPanel.py
--- a/controls/ProjectPropertiesPanel.py	Thu Sep 02 21:36:29 2021 +0200
+++ b/controls/ProjectPropertiesPanel.py	Thu Sep 02 22:18:14 2021 +0200
@@ -57,7 +57,7 @@
                 border |= wx.BOTTOM
 
             st = wx.StaticText(parent, label=label)
-            sizer.AddWindow(st, border=10,
+            sizer.Add(st, border=10,
                             flag=wx.ALIGN_CENTER_VERTICAL | border | wx.LEFT)
 
             tc = wx.TextCtrl(parent, style=wx.TE_PROCESS_ENTER)
@@ -65,7 +65,7 @@
             callback = self.GetTextCtrlChangedFunction(tc, name)
             self.Bind(wx.EVT_TEXT_ENTER, callback, tc)
             tc.Bind(wx.EVT_KILL_FOCUS, callback)
-            sizer.AddWindow(tc, border=10,
+            sizer.Add(tc, border=10,
                             flag=wx.GROW | border | wx.RIGHT)
 
     def __init__(self, parent, controller=None, window=None, enable_required=True, scrolling=True):
@@ -125,19 +125,19 @@
 
         pageSize_st = wx.StaticText(self.GraphicsPanel,
                                     label=_('Page Size (optional):'))
-        graphicpanel_sizer.AddWindow(
+        graphicpanel_sizer.Add(
             pageSize_st, border=10,
             flag=wx.ALIGN_CENTER_VERTICAL | wx.TOP | wx.LEFT | wx.RIGHT)
 
         pageSize_sizer = wx.FlexGridSizer(cols=2, hgap=5, rows=2, vgap=5)
         pageSize_sizer.AddGrowableCol(1)
-        graphicpanel_sizer.AddSizer(pageSize_sizer, border=10,
+        graphicpanel_sizer.Add(pageSize_sizer, border=10,
                                     flag=wx.GROW | wx.LEFT | wx.RIGHT)
 
         for name, label in [('PageWidth', _('Width:')),
                             ('PageHeight', _('Height:'))]:
             st = wx.StaticText(self.GraphicsPanel, label=label)
-            pageSize_sizer.AddWindow(st, border=12,
+            pageSize_sizer.Add(st, border=12,
                                      flag=wx.ALIGN_CENTER_VERTICAL | wx.LEFT)
 
             sp = wx.SpinCtrl(self.GraphicsPanel,
@@ -146,15 +146,15 @@
             callback = self.GetPageSizeChangedFunction(sp, name)
             self.Bind(wx.EVT_TEXT_ENTER, callback, sp)
             sp.Bind(wx.EVT_KILL_FOCUS, callback)
-            pageSize_sizer.AddWindow(sp, flag=wx.GROW)
+            pageSize_sizer.Add(sp, flag=wx.GROW)
 
         scaling_st = wx.StaticText(self.GraphicsPanel,
                                    label=_('Grid Resolution:'))
-        graphicpanel_sizer.AddWindow(scaling_st, border=10,
+        graphicpanel_sizer.Add(scaling_st, border=10,
                                      flag=wx.GROW | wx.LEFT | wx.RIGHT)
 
         scaling_nb = wx.Notebook(self.GraphicsPanel)
-        graphicpanel_sizer.AddWindow(scaling_nb, border=10,
+        graphicpanel_sizer.Add(scaling_nb, border=10,
                                      flag=wx.GROW | wx.BOTTOM | wx.LEFT | wx.RIGHT)
 
         self.Scalings = {}
@@ -173,7 +173,7 @@
                     border = wx.BOTTOM
 
                 st = wx.StaticText(scaling_panel, label=label)
-                scalingpanel_sizer.AddWindow(
+                scalingpanel_sizer.Add(
                     st, border=10,
                     flag=wx.ALIGN_CENTER_VERTICAL | border | wx.LEFT)
 
@@ -183,7 +183,7 @@
                 callback = self.GetScalingChangedFunction(sp, language, name)
                 self.Bind(wx.EVT_TEXT_ENTER, callback, sp)
                 sp.Bind(wx.EVT_KILL_FOCUS, callback)
-                scalingpanel_sizer.AddWindow(sp, border=10,
+                scalingpanel_sizer.Add(sp, border=10,
                                              flag=wx.GROW | border | wx.RIGHT)
 
             self.Scalings[language] = scaling_controls
@@ -206,18 +206,18 @@
 
         language_label = wx.StaticText(self.MiscellaneousPanel,
                                        label=_('Language (optional):'))
-        miscellaneouspanel_sizer.AddWindow(language_label, border=10,
+        miscellaneouspanel_sizer.Add(language_label, border=10,
                                            flag=wx.ALIGN_CENTER_VERTICAL | wx.TOP | wx.LEFT)
 
         self.Language = wx.ComboBox(self.MiscellaneousPanel,
                                     style=wx.CB_READONLY)
         self.Bind(wx.EVT_COMBOBOX, self.OnLanguageChanged, self.Language)
-        miscellaneouspanel_sizer.AddWindow(self.Language, border=10,
+        miscellaneouspanel_sizer.Add(self.Language, border=10,
                                            flag=wx.GROW | wx.TOP | wx.RIGHT)
 
         description_label = wx.StaticText(
             self.MiscellaneousPanel, label=_('Content Description (optional):'))
-        miscellaneouspanel_sizer.AddWindow(description_label, border=10,
+        miscellaneouspanel_sizer.Add(description_label, border=10,
                                            flag=wx.BOTTOM | wx.LEFT)
 
         self.ContentDescription = wx.TextCtrl(
@@ -227,7 +227,7 @@
                   self.ContentDescription)
         self.ContentDescription.Bind(wx.EVT_KILL_FOCUS,
                                      self.OnContentDescriptionChanged)
-        miscellaneouspanel_sizer.AddWindow(self.ContentDescription, border=10,
+        miscellaneouspanel_sizer.Add(self.ContentDescription, border=10,
                                            flag=wx.GROW | wx.BOTTOM | wx.RIGHT)
 
         self.AddPage(self.MiscellaneousPanel, _("Miscellaneous"))