--- a/libgui/src/gui-preferences-all.h	Sun Dec 22 17:40:15 2019 +0100
+++ b/libgui/src/gui-preferences-all.h	Sun Dec 22 17:42:42 2019 +0100
@@ -36,6 +36,7 @@
 #include "gui-preferences-pd.h"
 #include "gui-preferences-ve.h"
 #include "gui-preferences-sc.h"
+#include "gui-preferences-sd.h"
 #include "gui-preferences-ws.h"
 
 #endif

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libgui/src/gui-preferences-sd.h	Sun Dec 22 17:42:42 2019 +0100
@@ -0,0 +1,39 @@
+/*
+
+Copyright (C) 2017-2019 Torsten <ttl-octave@mailbox.org>
+
+This file is part of Octave.
+
+Octave is free software: you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+Octave is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with Octave; see the file COPYING.  If not, see
+<https://www.gnu.org/licenses/>.
+
+*/
+
+#if ! defined (octave_gui_preferences_sd_h)
+#define octave_gui_preferences_sd_h 1
+
+#include "gui-preferences.h"
+
+// Settings dialog
+
+const gui_pref
+sd_geometry ("settings/geometry", QVariant ());
+
+const gui_pref
+sd_last_tab ("settings/last_tab", QVariant (0));
+
+const gui_pref
+sd_last_editor_styles_tab ("settings/last_editor_styles_tab", QVariant (0));
+
+#endif

--- a/libgui/src/settings-dialog.cc	Sun Dec 22 17:40:15 2019 +0100
+++ b/libgui/src/settings-dialog.cc	Sun Dec 22 17:42:42 2019 +0100
@@ -504,8 +504,8 @@
              this, SLOT (button_clicked (QAbstractButton *)));
 
     // restore last geometry
-    if (settings->contains ("settings/geometry"))
-      restoreGeometry (settings->value ("settings/geometry").toByteArray ());
+    if (settings->contains (sd_geometry.key))
+      restoreGeometry (settings->value (sd_geometry).toByteArray ());
     else
       setGeometry (QRect (10,50,1000,600));
   }
@@ -517,7 +517,7 @@
         resource_manager& rmgr = m_octave_qobj.get_resource_manager ();
         gui_settings *settings = rmgr.get_settings ();
         if (settings)
-          tabWidget->setCurrentIndex (settings->value ("settings/last_tab", 0).toInt ());
+          tabWidget->setCurrentIndex (settings->value (sd_last_tab).toInt ());
       }
     else
       {
@@ -702,7 +702,7 @@
     scroll_area->setWidget (scroll_area_contents);
     tabs_editor_lexers->addTab (scroll_area, lexer->language ());
 
-    tabs_editor_lexers->setCurrentIndex (settings->value ("settings/last_editor_styles_tab", 0).toInt ());
+    tabs_editor_lexers->setCurrentIndex (settings->value (sd_last_editor_styles_tab).toInt ());
 
 #else
 
@@ -795,7 +795,7 @@
 
     lexer->writeSettings (*settings);
 
-    settings->setValue ("settings/last_editor_styles_tab",
+    settings->setValue (sd_last_editor_styles_tab.key,
                         tabs_editor_lexers->currentIndex ());
     settings->sync ();
 
@@ -1027,8 +1027,8 @@
     scmgr.write_shortcuts (settings, closing);
 
     // settings dialog's geometry
-    settings->setValue ("settings/last_tab", tabWidget->currentIndex ());
-    settings->setValue ("settings/geometry", saveGeometry ());
+    settings->setValue (sd_last_tab.key, tabWidget->currentIndex ());
+    settings->setValue (sd_geometry.key, saveGeometry ());
 
     settings->sync ();
   }