Index: source/tools/atlas/AtlasUI/CustomControls/SnapSplitterWindow/SnapSplitterWindow.h
===================================================================
--- source/tools/atlas/AtlasUI/CustomControls/SnapSplitterWindow/SnapSplitterWindow.h
+++ source/tools/atlas/AtlasUI/CustomControls/SnapSplitterWindow/SnapSplitterWindow.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2009 Wildfire Games.
+/* Copyright (C) 2020 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -20,17 +20,26 @@
 class SnapSplitterWindow : public wxSplitterWindow
 {
 public:
-	SnapSplitterWindow(wxWindow* parent, long style = wxSP_3D);
+	SnapSplitterWindow(wxWindow* parent, long style = wxSP_3D, const wxString& configPath = wxString());
+
 	void SetDefaultSashPosition(int sashPosition);
+
 	virtual bool SplitVertically(wxWindow* window1, wxWindow* window2, int sashPosition = 0);
 	virtual bool SplitHorizontally(wxWindow* window1, wxWindow* window2, int sashPosition = 0);
 
+	bool LoadSashPositionIfSaved(int* sashPosition);
+	void SaveSashPositionIfChanged();
+
+	void OnClose(wxCloseEvent& event);
+
 private:
 	void OnSashPosChanging(wxSplitterEvent& evt);
 	void OnDoubleClick(wxSplitterEvent& evt);
 
 	int m_DefaultSashPosition;
 	int m_SnapTolerance;
+	wxString m_ConfigPath;
+	bool m_SashPositionChanged;
 
 	DECLARE_EVENT_TABLE();
 };
Index: source/tools/atlas/AtlasUI/CustomControls/SnapSplitterWindow/SnapSplitterWindow.cpp
===================================================================
--- source/tools/atlas/AtlasUI/CustomControls/SnapSplitterWindow/SnapSplitterWindow.cpp
+++ source/tools/atlas/AtlasUI/CustomControls/SnapSplitterWindow/SnapSplitterWindow.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2009 Wildfire Games.
+/* Copyright (C) 2020 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -19,15 +19,19 @@
 
 #include "SnapSplitterWindow.h"
 
+#include <wx/confbase.h>
+
 BEGIN_EVENT_TABLE(SnapSplitterWindow, wxSplitterWindow)
 	EVT_SPLITTER_SASH_POS_CHANGING(wxID_ANY, SnapSplitterWindow::OnSashPosChanging)
 	EVT_SPLITTER_DCLICK(wxID_ANY, SnapSplitterWindow::OnDoubleClick)
 END_EVENT_TABLE()
 
-SnapSplitterWindow::SnapSplitterWindow(wxWindow* parent, long style)
+SnapSplitterWindow::SnapSplitterWindow(wxWindow* parent, long style, const wxString& configPath)
 	: wxSplitterWindow(parent, wxID_ANY, wxDefaultPosition, wxDefaultSize,
 					   style | wxSP_LIVE_UPDATE),
-					   m_SnapTolerance(16)
+					   m_SnapTolerance(16),
+					   m_ConfigPath(configPath),
+					   m_SashPositionChanged(false)
 {
 	// Set min size, to disable unsplitting
 	SetMinimumPaneSize(32);
@@ -50,6 +54,9 @@
 {
 	if (sashPosition == 0)
 		sashPosition = m_DefaultSashPosition;
+
+	LoadSashPositionIfSaved(&sashPosition);
+
 	return wxSplitterWindow::SplitVertically(window1, window2, sashPosition);
 }
 
@@ -57,6 +64,9 @@
 {
 	if (sashPosition == 0)
 		sashPosition = m_DefaultSashPosition;
+
+	LoadSashPositionIfSaved(&sashPosition);
+
 	return wxSplitterWindow::SplitHorizontally(window1, window2, sashPosition);
 }
 
@@ -69,6 +79,8 @@
 	{
 		evt.SetSashPosition(defaultPos);
 	}
+
+	m_SashPositionChanged = true;
 }
 
 void SnapSplitterWindow::OnDoubleClick(wxSplitterEvent& WXUNUSED(evt))
@@ -76,3 +88,25 @@
 	int defaultPos = ConvertSashPosition(m_DefaultSashPosition);
 	SetSashPosition(defaultPos);
 }
+
+bool SnapSplitterWindow::LoadSashPositionIfSaved(int* sashPosition)
+{
+	// We use the same config path for both horizontal and vertical splits,
+	// because we can't have both at the same moment.
+	wxConfigBase* cfg = wxConfigBase::Get(false);
+	// wxConfigBase::Read doesn't modify the value if there was an error.
+	return cfg && cfg->Read(m_ConfigPath, sashPosition);
+}
+
+void SnapSplitterWindow::SaveSashPositionIfChanged()
+{
+	wxConfigBase* cfg = wxConfigBase::Get(false);
+	if (!cfg || !m_SashPositionChanged)
+		return;
+	cfg->Write(m_ConfigPath, GetSashPosition());
+}
+
+void SnapSplitterWindow::OnClose(wxCloseEvent& WXUNUSED(event))
+{
+	SaveSashPositionIfChanged();
+}
Index: source/tools/atlas/AtlasUI/ScenarioEditor/SectionLayout.cpp
===================================================================
--- source/tools/atlas/AtlasUI/ScenarioEditor/SectionLayout.cpp
+++ source/tools/atlas/AtlasUI/ScenarioEditor/SectionLayout.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2017 Wildfire Games.
+/* Copyright (C) 2020 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -17,15 +17,11 @@
 
 #include "precompiled.h"
 
-#include "wx/filename.h"
-#include "wx/wfstream.h"
-
 #include "SectionLayout.h"
 
 #include "CustomControls/SnapSplitterWindow/SnapSplitterWindow.h"
-
+#include "General/Datafile.h"
 #include "ScenarioEditor.h"
-
 #include "Sections/Cinema/Cinema.h"
 #include "Sections/Environment/Environment.h"
 #include "Sections/Map/Map.h"
@@ -33,7 +29,8 @@
 #include "Sections/Player/Player.h"
 #include "Sections/Terrain/Terrain.h"
 
-#include "General/Datafile.h"
+#include <wx/filename.h>
+#include <wx/wfstream.h>
 
 //////////////////////////////////////////////////////////////////////////
 
@@ -257,8 +254,10 @@
 
 void SectionLayout::SetWindow(wxWindow* window)
 {
-	m_HorizSplitter = new SnapSplitterWindow(window, wxSP_NOBORDER);
-	m_VertSplitter = new SnapSplitterWindow(m_HorizSplitter, wxSP_3D);
+	m_HorizSplitter = new SnapSplitterWindow(
+		window, wxSP_NOBORDER, _T("Scenario Editor/Layout/VerticalSplitter"));
+	m_VertSplitter = new SnapSplitterWindow(
+		m_HorizSplitter, wxSP_3D, _T("Scenario Editor/Layout/HorizontalSplitter"));
 }
 
 wxWindow* SectionLayout::GetCanvasParent()