diff --git a/src/gui/app.cc b/src/gui/app.cc
index 734909a344..309ceed6b2 100644
--- a/src/gui/app.cc
+++ b/src/gui/app.cc
@@ -2,7 +2,7 @@
 // This file is part of Gambit
 // Copyright (c) 1994-2026, The Gambit Project (https://www.gambit-project.org)
 //
-// FILE: src/gui/gambit.cc
+// FILE: src/gui/app.cc
 // Implementation of main wxApp class
 //
 // This program is free software; you can redistribute it and/or modify
@@ -20,8 +20,6 @@
 // Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 //
 
-#include <fstream>
-
 #include <wx/wxprec.h>
 #ifndef WX_PRECOMP
 #include <wx/wx.h>
@@ -181,48 +179,35 @@ class FileErrorDialog final : public wxDialog {
 
 AppLoadResult Application::LoadFile(const wxString &p_filename, wxWindow *p_parent)
 {
-  std::ifstream infile(p_filename.mb_str());
-  if (!infile.good()) {
+  const auto [result, doc] = GameDocument::Load(p_filename);
+
+  switch (result) {
+  case GameDocument::LoadResult::OpenFailed:
     FileErrorDialog(p_parent, _("Unable to open file"),
                     _("Gambit could not open this file for reading."), p_filename)
         .ShowModal();
     return AppLoadResult::OpenFailed;
-  }
 
-  auto *doc = new GameDocument(NewTree());
-  if (doc->LoadWorkspace(p_filename)) {
-    doc->SetFilename(p_filename);
-    m_fileHistory.AddFileToHistory(p_filename);
-    m_fileHistory.Save(*wxConfigBase::Get());
-    (void)new GameFrame(nullptr, doc);
-    return AppLoadResult::Success;
-  }
-  delete doc;
-
-  try {
-    const Game game = ReadGame(infile);
-    if (game->IsAgg()) {
-      FileErrorDialog(p_parent, _("Unsupported game representation"),
-                      _("Action graph games are not currently supported by the "
-                        "graphical interface."),
-                      p_filename)
-          .ShowModal();
-      return AppLoadResult::UnsupportedRepresentation;
-    }
+  case GameDocument::LoadResult::ParseFailed:
+    FileErrorDialog(p_parent, _("Unable to read file"),
+                    _("File is not in a format Gambit recognizes."), p_filename)
+        .ShowModal();
+    return AppLoadResult::ParseFailed;
 
+  case GameDocument::LoadResult::UnsupportedRepresentation:
+    FileErrorDialog(p_parent, _("Unsupported game representation"),
+                    _("Action graph games are not currently supported by the "
+                      "graphical interface."),
+                    p_filename)
+        .ShowModal();
+    return AppLoadResult::UnsupportedRepresentation;
+
+  case GameDocument::LoadResult::Success:
     m_fileHistory.AddFileToHistory(p_filename);
     m_fileHistory.Save(*wxConfigBase::Get());
-    doc = new GameDocument(game);
-    doc->SetFilename(p_filename);
     (void)new GameFrame(nullptr, doc);
     return AppLoadResult::Success;
   }
-  catch (InvalidFileException &) {
-    FileErrorDialog(p_parent, _("Unable to read file"),
-                    _("File is not in a format Gambit recognizes."), p_filename)
-        .ShowModal();
-    return AppLoadResult::ParseFailed;
-  }
 }
 
 void Application::SetCurrentDir(const wxString &p_dir)
diff --git a/src/gui/dlefglogit.cc b/src/gui/dlefglogit.cc
index 6561719063..0bb3484dff 100644
--- a/src/gui/dlefglogit.cc
+++ b/src/gui/dlefglogit.cc
@@ -46,14 +46,14 @@ namespace Gambit::GUI {
 //! isn't resized/repainted on every single profile received.
 //!
 class LogitBehavTable final : public wxGridTableBase {
-  GameDocument *m_doc;
+  std::shared_ptr<GameDocument> m_doc;
   Array<double> m_lambdas;
   Array<std::shared_ptr<MixedBehaviorProfile<double>>> m_profiles;
   int m_numCols{0};
   int m_numRows{0};
 
 public:
-  explicit LogitBehavTable(GameDocument *p_doc) : m_doc(p_doc) {}
+  explicit LogitBehavTable(const std::shared_ptr<GameDocument> &p_doc) : m_doc(p_doc) {}
 
   int GetNumberRows() override { return m_numRows; }
   int GetNumberCols() override { return m_numCols; }
@@ -172,7 +172,7 @@ class LogitBehavGrid final : public wxGrid {
   //@}
 
 public:
-  LogitBehavGrid(wxWindow *p_parent, GameDocument *p_doc)
+  LogitBehavGrid(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc)
     : wxGrid(p_parent, wxID_ANY), m_gridTable(new LogitBehavTable(p_doc))
   {
     SetTable(m_gridTable, true);
@@ -258,7 +258,7 @@ class LogitBehavThreadRunner final : public wxThread {
   void RequestCancel() { m_cancel.RequestCancel(); }
 };
 
-LogitBehavDialog::LogitBehavDialog(wxWindow *p_parent, GameDocument *p_doc)
+LogitBehavDialog::LogitBehavDialog(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc)
   : wxDialog(p_parent, wxID_ANY, wxT("Compute quantal response equilibria"), wxDefaultPosition),
     m_doc(p_doc), m_behavList(new LogitBehavGrid(this, m_doc))
 {
diff --git a/src/gui/dlefglogit.h b/src/gui/dlefglogit.h
index 43844818e2..727463dedb 100644
--- a/src/gui/dlefglogit.h
+++ b/src/gui/dlefglogit.h
@@ -30,7 +30,7 @@ class LogitBehavGrid;
 class LogitBehavThreadRunner;
 
 class LogitBehavDialog final : public wxDialog {
-  GameDocument *m_doc;
+  std::shared_ptr<GameDocument> m_doc;
   std::unique_ptr<LogitBehavThreadRunner> m_runner;
   LogitBehavGrid *m_behavList;
   wxStaticText *m_statusText;
@@ -47,7 +47,7 @@ class LogitBehavDialog final : public wxDialog {
   void Start();
 
 public:
-  LogitBehavDialog(wxWindow *p_parent, GameDocument *p_doc);
+  LogitBehavDialog(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc);
   ~LogitBehavDialog() override;
 };
 
diff --git a/src/gui/dlgameprop.cc b/src/gui/dlgameprop.cc
index 8deaa1ef9c..40b168646e 100644
--- a/src/gui/dlgameprop.cc
+++ b/src/gui/dlgameprop.cc
@@ -75,7 +75,7 @@ class PlayerLabelPanel final : public wxPanel {
   };
 
 private:
-  GameDocument *m_doc;
+  std::shared_ptr<GameDocument> m_doc;
   std::vector<Row> m_rows;
   wxColour m_defaultBg;
   std::function<void()> m_onChanged;
@@ -87,7 +87,7 @@ class PlayerLabelPanel final : public wxPanel {
   wxBitmapButton *MakeColorButton(int p_index);
 
 public:
-  PlayerLabelPanel(wxWindow *p_parent, GameDocument *p_doc,
+  PlayerLabelPanel(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc,
                    const std::function<void()> &p_onChanged);
 
   int NumRows() const { return static_cast<int>(m_rows.size()); }
@@ -106,7 +106,7 @@ class PlayerLabelPanel final : public wxPanel {
   wxString ValidateLabels();
 };
 
-PlayerLabelPanel::PlayerLabelPanel(wxWindow *p_parent, GameDocument *p_doc,
+PlayerLabelPanel::PlayerLabelPanel(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc,
                                    const std::function<void()> &p_onChanged)
   : wxPanel(p_parent, wxID_ANY), m_doc(p_doc), m_onChanged(p_onChanged)
 {
@@ -247,7 +247,8 @@ wxString PlayerLabelPanel::ValidateLabels()
 //                   class GamePropertiesDialog
 //========================================================================
 
-GamePropertiesDialog::GamePropertiesDialog(wxWindow *p_parent, GameDocument *p_doc)
+GamePropertiesDialog::GamePropertiesDialog(wxWindow *p_parent,
+                                           const std::shared_ptr<GameDocument> &p_doc)
   : wxDialog(p_parent, wxID_ANY, _("Game properties"), wxDefaultPosition, wxDefaultSize,
              wxDEFAULT_DIALOG_STYLE | wxRESIZE_BORDER),
     m_doc(p_doc)
diff --git a/src/gui/dlgameprop.h b/src/gui/dlgameprop.h
index d89533a4b6..92db9f6791 100644
--- a/src/gui/dlgameprop.h
+++ b/src/gui/dlgameprop.h
@@ -28,7 +28,7 @@ namespace Gambit::GUI {
 class PlayerLabelPanel;
 
 class GamePropertiesDialog final : public wxDialog {
-  GameDocument *m_doc;
+  std::shared_ptr<GameDocument> m_doc;
   wxTextCtrl *m_title, *m_comment;
   PlayerLabelPanel *m_playerPanel;
   wxStaticText *m_errorText;
@@ -37,7 +37,7 @@ class GamePropertiesDialog final : public wxDialog {
 
 public:
   // Lifecycle
-  GamePropertiesDialog(wxWindow *p_parent, GameDocument *p_doc);
+  GamePropertiesDialog(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc);
 
   // Data access (only valid when ShowModal() returns with wxID_OK)
   wxString GetTitle() const override { return m_title->GetValue(); }
diff --git a/src/gui/dlinsertmove.cc b/src/gui/dlinsertmove.cc
index b0d18e1097..d8e0d3aed0 100644
--- a/src/gui/dlinsertmove.cc
+++ b/src/gui/dlinsertmove.cc
@@ -32,7 +32,7 @@ namespace Gambit::GUI {
 //                   InsertMoveDialog: Member functions
 //=========================================================================
 
-InsertMoveDialog::InsertMoveDialog(wxWindow *p_parent, GameDocument *p_doc)
+InsertMoveDialog::InsertMoveDialog(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc)
   : wxDialog(p_parent, wxID_ANY, _("Insert Move"), wxDefaultPosition), m_doc(p_doc)
 {
   m_playerItem = new wxChoice(this, wxID_ANY);
diff --git a/src/gui/dlinsertmove.h b/src/gui/dlinsertmove.h
index 44616a313f..d9c8dbd7bd 100644
--- a/src/gui/dlinsertmove.h
+++ b/src/gui/dlinsertmove.h
@@ -29,7 +29,7 @@
 namespace Gambit::GUI {
 
 class InsertMoveDialog final : public wxDialog {
-  GameDocument *m_doc;
+  std::shared_ptr<GameDocument> m_doc;
 
   wxChoice *m_playerItem, *m_infosetItem;
   wxSpinCtrl *m_actions;
@@ -39,7 +39,7 @@ class InsertMoveDialog final : public wxDialog {
 
 public:
   // Constructor
-  InsertMoveDialog(wxWindow *, GameDocument *);
+  InsertMoveDialog(wxWindow *, const std::shared_ptr<GameDocument> &);
 
   // Data access (only valid if ShowModal() returns wxID_OK.
   // If GetInfoset() returns null, user selected "new infoset"
diff --git a/src/gui/dlnash.cc b/src/gui/dlnash.cc
index 50ebef0473..d16229b5eb 100644
--- a/src/gui/dlnash.cc
+++ b/src/gui/dlnash.cc
@@ -291,7 +291,7 @@ wxString ParameterDescription(const NashMethodSpec &p_method)
 
 } // namespace
 
-NashChoiceDialog::NashChoiceDialog(wxWindow *p_parent, GameDocument *p_doc)
+NashChoiceDialog::NashChoiceDialog(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc)
   : wxDialog(p_parent, wxID_ANY, wxT("Compute Nash equilibria"), wxDefaultPosition), m_doc(p_doc)
 {
   auto *topSizer = new wxBoxSizer(wxVERTICAL);
@@ -432,10 +432,10 @@ std::shared_ptr<AnalysisOutput> NashChoiceDialog::GetCommand() const
   const bool useBehavior = computation.representation == NashRepresentation::Behavior;
   std::shared_ptr<AnalysisOutput> output;
   if (UsesRationalOutput(computation.method)) {
-    output = std::make_shared<AnalysisProfileList<Rational>>(m_doc, useBehavior);
+    output = std::make_shared<AnalysisProfileList<Rational>>(m_doc.get(), useBehavior);
   }
   else {
-    output = std::make_shared<AnalysisProfileList<double>>(m_doc, useBehavior);
+    output = std::make_shared<AnalysisProfileList<double>>(m_doc.get(), useBehavior);
   }
 
   wxString count;
diff --git a/src/gui/dlnash.h b/src/gui/dlnash.h
index ee55b3881f..71e99c6559 100644
--- a/src/gui/dlnash.h
+++ b/src/gui/dlnash.h
@@ -27,7 +27,7 @@
 
 namespace Gambit::GUI {
 class NashChoiceDialog final : public wxDialog {
-  GameDocument *m_doc;
+  std::shared_ptr<GameDocument> m_doc;
   wxChoice *m_countChoice, *m_methodChoice, *m_repChoice;
 
   // Event handlers
@@ -38,7 +38,7 @@ class NashChoiceDialog final : public wxDialog {
   NashComputationSpec GetComputation() const;
 
 public:
-  NashChoiceDialog(wxWindow *, GameDocument *);
+  NashChoiceDialog(wxWindow *, const std::shared_ptr<GameDocument> &);
 
   std::shared_ptr<AnalysisOutput> GetCommand() const;
 
diff --git a/src/gui/dlnashmon.cc b/src/gui/dlnashmon.cc
index b1491f5534..91746bf96a 100644
--- a/src/gui/dlnashmon.cc
+++ b/src/gui/dlnashmon.cc
@@ -302,7 +302,7 @@ class SolverThreadRunner final : public wxThread {
 };
 
 class NashMonitorDialog final : public wxDialog {
-  GameDocument *m_doc;
+  std::shared_ptr<GameDocument> m_doc;
   std::unique_ptr<class ExternalProcessRunner> m_runner;
   std::unique_ptr<class SolverThreadRunner> m_threadRunner;
   wxWindow *m_profileList;
@@ -354,11 +354,12 @@ class NashMonitorDialog final : public wxDialog {
   }
 
 public:
-  NashMonitorDialog(wxWindow *p_parent, GameDocument *p_doc,
+  NashMonitorDialog(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc,
                     const std::shared_ptr<AnalysisOutput> &p_command);
 };
 
-NashMonitorDialog::NashMonitorDialog(wxWindow *p_parent, GameDocument *p_doc,
+NashMonitorDialog::NashMonitorDialog(wxWindow *p_parent,
+                                     const std::shared_ptr<GameDocument> &p_doc,
                                      const std::shared_ptr<AnalysisOutput> &p_command)
   : wxDialog(p_parent, wxID_ANY, wxT("Computing Nash equilibria"), wxDefaultPosition),
     m_doc(p_doc), m_output(p_command)
@@ -547,7 +548,7 @@ void NashMonitorDialog::OnClose(wxCloseEvent &p_event)
 
 namespace Gambit::GUI {
 
-void ShowNashMonitorDialog(wxWindow *p_parent, GameDocument *p_doc,
+void ShowNashMonitorDialog(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc,
                            const std::shared_ptr<AnalysisOutput> &p_command)
 {
   NashMonitorDialog dialog(p_parent, p_doc, p_command);
diff --git a/src/gui/dlnfglogit.cc b/src/gui/dlnfglogit.cc
index 1a576e1a3d..51d1e314bf 100644
--- a/src/gui/dlnfglogit.cc
+++ b/src/gui/dlnfglogit.cc
@@ -46,14 +46,14 @@ namespace Gambit::GUI {
 //! isn't resized/repainted on every single profile received.
 //!
 class LogitMixedTable final : public wxGridTableBase {
-  GameDocument *m_doc;
+  std::shared_ptr<GameDocument> m_doc;
   Array<double> m_lambdas;
   Array<std::shared_ptr<MixedStrategyProfile<double>>> m_profiles;
   int m_numCols{0};
   int m_numRows{0};
 
 public:
-  explicit LogitMixedTable(GameDocument *p_doc) : m_doc(p_doc) {}
+  explicit LogitMixedTable(const std::shared_ptr<GameDocument> &p_doc) : m_doc(p_doc) {}
 
   int GetNumberRows() override { return m_numRows; }
   int GetNumberCols() override { return m_numCols; }
@@ -175,7 +175,7 @@ class LogitMixedGrid final : public wxGrid {
   //@}
 
 public:
-  LogitMixedGrid(wxWindow *p_parent, GameDocument *p_doc)
+  LogitMixedGrid(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc)
     : wxGrid(p_parent, wxID_ANY), m_gridTable(new LogitMixedTable(p_doc))
   {
     SetTable(m_gridTable, true);
@@ -261,7 +261,7 @@ class LogitMixedThreadRunner final : public wxThread {
   void RequestCancel() { m_cancel.RequestCancel(); }
 };
 
-LogitMixedDialog::LogitMixedDialog(wxWindow *p_parent, GameDocument *p_doc)
+LogitMixedDialog::LogitMixedDialog(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc)
   : wxDialog(p_parent, wxID_ANY, wxT("Compute quantal response equilibria"), wxDefaultPosition),
     m_doc(p_doc), m_mixedList(new LogitMixedGrid(this, m_doc))
 {
@@ -412,7 +412,7 @@ void LogitMixedDialog::OnSave(wxCommandEvent &)
   }
 }
 
-void LogitStrategic(wxWindow *p_parent, GameDocument *p_doc)
+void LogitStrategic(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc)
 {
   LogitMixedDialog(p_parent, p_doc).ShowModal();
 }
diff --git a/src/gui/dlnfglogit.h b/src/gui/dlnfglogit.h
index 5cae090259..28788e1f83 100644
--- a/src/gui/dlnfglogit.h
+++ b/src/gui/dlnfglogit.h
@@ -30,7 +30,7 @@ class LogitMixedGrid;
 class LogitMixedThreadRunner;
 
 class LogitMixedDialog final : public wxDialog {
-  GameDocument *m_doc;
+  std::shared_ptr<GameDocument> m_doc;
   std::unique_ptr<LogitMixedThreadRunner> m_runner;
   LogitMixedGrid *m_mixedList;
   wxStaticText *m_statusText;
@@ -47,11 +47,11 @@ class LogitMixedDialog final : public wxDialog {
   void Start();
 
 public:
-  LogitMixedDialog(wxWindow *p_parent, GameDocument *p_doc);
+  LogitMixedDialog(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc);
   ~LogitMixedDialog() override;
 };
 
-void LogitStrategic(wxWindow *p_parent, GameDocument *p_doc);
+void LogitStrategic(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc);
 
 } // namespace Gambit::GUI
 
diff --git a/src/gui/efgdisplay.cc b/src/gui/efgdisplay.cc
index c4648ac3a9..09fe1f3b39 100644
--- a/src/gui/efgdisplay.cc
+++ b/src/gui/efgdisplay.cc
@@ -62,7 +62,7 @@ END_EVENT_TABLE()
 //                EfgDisplay: Constructor and destructor
 //----------------------------------------------------------------------
 
-EfgDisplay::EfgDisplay(wxWindow *p_parent, GameDocument *p_doc)
+EfgDisplay::EfgDisplay(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc)
   : wxScrolledWindow(p_parent), GameView(p_doc), m_layout(p_doc), m_zoom(100)
 {
   wxWindow::SetBackgroundColour(wxColour(250, 250, 250));
diff --git a/src/gui/efgdisplay.h b/src/gui/efgdisplay.h
index 2731b0103b..76b84465c0 100644
--- a/src/gui/efgdisplay.h
+++ b/src/gui/efgdisplay.h
@@ -125,7 +125,7 @@ class EfgDisplay final : public wxScrolledWindow, public GameView {
   void ZoomByFactor(double p_factor, const wxPoint &p_clientPoint);
 
 public:
-  EfgDisplay(wxWindow *p_parent, GameDocument *p_doc);
+  EfgDisplay(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc);
 
   void OnDraw(wxDC &dc) override;
   void OnDraw(wxDC &, double);
diff --git a/src/gui/efgdragdrop.cc b/src/gui/efgdragdrop.cc
index eaa5a785a5..0288a8abc3 100644
--- a/src/gui/efgdragdrop.cc
+++ b/src/gui/efgdragdrop.cc
@@ -41,7 +41,7 @@ namespace Gambit::GUI {
 
 class TreeDropTarget : public wxTextDropTarget {
   EfgDisplay *m_owner;
-  GameDocument *m_model;
+  std::shared_ptr<GameDocument> m_model;
 
   bool OnDropOutcome(const GameNode &p_node, const wxString &p_text, const wxPoint &p_pos);
   bool OnDropTreeNode(const GameNode &p_node, const wxString &p_text, const wxPoint &p_pos);
diff --git a/src/gui/efglayout.h b/src/gui/efglayout.h
index 784258e0ab..1767af92f9 100644
--- a/src/gui/efglayout.h
+++ b/src/gui/efglayout.h
@@ -177,7 +177,7 @@ class TreeLayout final : public GameView {
   void BuildNodeList(const Game &);
 
 public:
-  explicit TreeLayout(GameDocument *p_doc) : GameView(p_doc) {}
+  explicit TreeLayout(const std::shared_ptr<GameDocument> &p_doc) : GameView(p_doc) {}
   ~TreeLayout() override = default;
 
   void Layout(const Game &);
diff --git a/src/gui/efgpanel.cc b/src/gui/efgpanel.cc
index 18abd1e599..6f4a739669 100644
--- a/src/gui/efgpanel.cc
+++ b/src/gui/efgpanel.cc
@@ -47,7 +47,7 @@ EVT_MENU(GBT_MENU_VIEW_ZOOM100, EfgPanel::OnViewZoom100)
 EVT_MENU(GBT_MENU_VIEW_ZOOMFIT, EfgPanel::OnViewZoomFit)
 END_EVENT_TABLE()
 
-EfgPanel::EfgPanel(wxWindow *p_parent, GameDocument *p_doc)
+EfgPanel::EfgPanel(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc)
   : wxPanel(p_parent, wxID_ANY), GameView(p_doc), m_treeWindow(new EfgDisplay(this, m_doc))
 {
   auto *topSizer = new wxBoxSizer(wxVERTICAL);
diff --git a/src/gui/efgpanel.h b/src/gui/efgpanel.h
index b2bf2c6638..15710530e2 100644
--- a/src/gui/efgpanel.h
+++ b/src/gui/efgpanel.h
@@ -45,7 +45,7 @@ class EfgPanel final : public wxPanel, public GameView {
   //@}
 
 public:
-  EfgPanel(wxWindow *p_parent, GameDocument *p_doc);
+  EfgPanel(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc);
   ~EfgPanel() override = default;
 
   /// @name Exporting/printing graphics
diff --git a/src/gui/efgprofile.cc b/src/gui/efgprofile.cc
index f596a3bbfb..43336acfef 100644
--- a/src/gui/efgprofile.cc
+++ b/src/gui/efgprofile.cc
@@ -32,7 +32,8 @@ namespace Gambit::GUI {
 //              class BehaviorProfileList: Member functions
 //-------------------------------------------------------------------------
 
-MixedBehaviorProfileList::MixedBehaviorProfileList(wxWindow *p_parent, GameDocument *p_doc)
+MixedBehaviorProfileList::MixedBehaviorProfileList(wxWindow *p_parent,
+                                                   const std::shared_ptr<GameDocument> &p_doc)
   : wxGrid(p_parent, wxID_ANY), GameView(p_doc)
 {
   CreateGrid(0, 0);
@@ -77,7 +78,7 @@ void MixedBehaviorProfileList::OnSelectCell(wxGridEvent &p_event)
   ClearSelection();
 }
 
-static wxColour GetPlayerColor(const GameDocument *p_doc, int p_index)
+static wxColour GetPlayerColor(const std::shared_ptr<GameDocument> &p_doc, int p_index)
 {
   const GameAction action = p_doc->GetAction(p_index + 1);
   return p_doc->GetStyle().GetPlayerColor(action->GetInfoset()->GetPlayer());
diff --git a/src/gui/efgprofile.h b/src/gui/efgprofile.h
index ca492469cd..f21925bc9b 100644
--- a/src/gui/efgprofile.h
+++ b/src/gui/efgprofile.h
@@ -42,7 +42,7 @@ class MixedBehaviorProfileList final : public wxGrid, public GameView {
   void OnUpdate() override;
 
 public:
-  MixedBehaviorProfileList(wxWindow *p_parent, GameDocument *p_doc);
+  MixedBehaviorProfileList(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc);
   ~MixedBehaviorProfileList() override;
 };
 } // namespace Gambit::GUI
diff --git a/src/gui/efgtooltip.cc b/src/gui/efgtooltip.cc
index dd3d4d09ba..96c41b29c2 100644
--- a/src/gui/efgtooltip.cc
+++ b/src/gui/efgtooltip.cc
@@ -36,7 +36,7 @@ namespace Gambit::GUI {
 
 class OutcomeEditorPopup : public wxPopupTransientWindow {
 public:
-  OutcomeEditorPopup(EfgDisplay *p_owner, GameDocument *p_doc);
+  OutcomeEditorPopup(EfgDisplay *p_owner, const std::shared_ptr<GameDocument> &p_doc);
 
   void BeginEdit(const GameNode &p_node, int p_initialPlayer = 0);
   bool Commit();
@@ -63,7 +63,7 @@ class OutcomeEditorPopup : public wxPopupTransientWindow {
   void RestoreAfterFailedCommit(wxTextCtrl *p_invalidCtrl);
 
   EfgDisplay *m_owner;
-  GameDocument *m_doc;
+  std::shared_ptr<GameDocument> m_doc;
 
   GameNode m_node;
 
@@ -80,7 +80,8 @@ class OutcomeEditorPopup : public wxPopupTransientWindow {
   bool m_restoringAfterFailedCommit{false};
 };
 
-OutcomeEditorPopup::OutcomeEditorPopup(EfgDisplay *p_owner, GameDocument *p_doc)
+OutcomeEditorPopup::OutcomeEditorPopup(EfgDisplay *p_owner,
+                                       const std::shared_ptr<GameDocument> &p_doc)
   : wxPopupTransientWindow(p_owner, wxBORDER_NONE), m_owner(p_owner), m_doc(p_doc),
     m_contentPanel(nullptr), m_labelCtrl(nullptr), m_errorText(nullptr)
 {
@@ -423,7 +424,7 @@ void OutcomeEditorPopup::RestoreAfterFailedCommit(wxTextCtrl *p_invalidCtrl)
 // left-hand player panel.
 class NodeInfoPopup : public wxPopupTransientWindow {
 public:
-  NodeInfoPopup(EfgDisplay *p_owner, GameDocument *p_doc);
+  NodeInfoPopup(EfgDisplay *p_owner, const std::shared_ptr<GameDocument> &p_doc);
 
   void ShowForNode(const GameNode &p_node);
 
@@ -432,7 +433,7 @@ class NodeInfoPopup : public wxPopupTransientWindow {
   void PositionPopup();
 
   EfgDisplay *m_owner;
-  GameDocument *m_doc;
+  std::shared_ptr<GameDocument> m_doc;
 
   GameNode m_node;
 
@@ -452,7 +453,7 @@ class NodeInfoPopup : public wxPopupTransientWindow {
   wxStaticText *m_beliefText;
 };
 
-NodeInfoPopup::NodeInfoPopup(EfgDisplay *p_owner, GameDocument *p_doc)
+NodeInfoPopup::NodeInfoPopup(EfgDisplay *p_owner, const std::shared_ptr<GameDocument> &p_doc)
   : wxPopupTransientWindow(p_owner, wxBORDER_NONE), m_owner(p_owner), m_doc(p_doc)
 {
   SetBackgroundColour(wxSystemSettings::GetColour(wxSYS_COLOUR_BTNSHADOW));
diff --git a/src/gui/gamedoc.cc b/src/gui/gamedoc.cc
index 53065bb2fb..f37fdb77a3 100644
--- a/src/gui/gamedoc.cc
+++ b/src/gui/gamedoc.cc
@@ -214,32 +214,44 @@ GameDocument::GameDocument(Game p_game)
 
 GameDocument::~GameDocument() { wxGetApp().RemoveDocument(this); }
 
-bool GameDocument::LoadWorkspace(const wxString &p_filename)
+GameDocument::LoadOutcome GameDocument::Load(const wxString &p_filename)
 {
   std::ifstream input(p_filename.mb_str());
   if (!input) {
-    return false;
+    return {LoadResult::OpenFailed, nullptr};
   }
 
-  LegacyWorkspaceFile workspace;
+  // First, see whether this is a Gambit workspace (.gbt) file.
   try {
-    workspace = Gambit::ReadLegacyWorkspace(input);
+    const LegacyWorkspaceFile workspace = ReadLegacyWorkspace(input);
+    std::istringstream game_text(workspace.game);
+    auto doc = std::make_shared<GameDocument>(ReadGame(game_text));
+    if (doc->m_workspace.Load(workspace.analyses)) {
+      doc->m_style.Load(workspace);
+      doc->SetFilename(p_filename);
+      return {LoadResult::Success, doc};
+    }
   }
-  catch (const std::runtime_error &) {
-    return false;
+  catch (const std::exception &) {
+    // Not a recognized (or not fully valid) workspace file; fall through to
+    // try it as a bare game file instead.
   }
+
+  // Not a (valid) workspace -- try reading it as a bare .efg/.nfg file.
+  input.clear();
+  input.seekg(0);
   try {
-    std::istringstream game_text(workspace.game);
-    m_game = ReadGame(game_text);
-  }
-  catch (...) {
-    return false;
+    const Game game = ReadGame(input);
+    if (game->IsAgg()) {
+      return {LoadResult::UnsupportedRepresentation, nullptr};
+    }
+    auto doc = std::make_shared<GameDocument>(game);
+    doc->SetFilename(p_filename);
+    return {LoadResult::Success, doc};
   }
-  if (!m_workspace.Load(workspace.analyses)) {
-    return false;
+  catch (const InvalidFileException &) {
+    return {LoadResult::ParseFailed, nullptr};
   }
-  m_style.Load(workspace);
-  return true;
 }
 
 void GameDocument::SaveWorkspace(std::ostream &p_file) const
diff --git a/src/gui/gamedoc.h b/src/gui/gamedoc.h
index d501ad072e..580ccb6ad5 100644
--- a/src/gui/gamedoc.h
+++ b/src/gui/gamedoc.h
@@ -214,9 +214,6 @@ class GameDocument {
   void RemoveView(GameView *p_view)
   {
     m_views.erase(std::find(m_views.begin(), m_views.end(), p_view));
-    if (m_views.empty()) {
-      delete this;
-    }
   }
 
   Game m_game;
@@ -232,15 +229,23 @@ class GameDocument {
 
 public:
   explicit GameDocument(Game p_game);
+  GameDocument(const GameDocument &) = delete;
+  GameDocument &operator=(const GameDocument &) = delete;
   ~GameDocument();
 
   //!
   //! @name Reading and writing savefiles
   //!
   //@{
-  /// Load workspace from the specified file (which should be a .gbt file)
-  /// Returns true if successful, false if error
-  bool LoadWorkspace(const wxString &p_filename);
+  enum class LoadResult { Success, OpenFailed, ParseFailed, UnsupportedRepresentation };
+  struct LoadOutcome {
+    LoadResult result;
+    std::shared_ptr<GameDocument> document; ///< non-null iff result == LoadResult::Success
+  };
+  /// Attempt to construct a document by reading `p_filename`, trying it first as a
+  /// Gambit workspace (.gbt) and then as a bare game (.efg/.nfg) file.
+  static LoadOutcome Load(const wxString &p_filename);
+
   void SaveWorkspace(std::ostream &) const;
   //@}
 
@@ -345,16 +350,16 @@ class GameDocument {
   void DoAnalysisOutputChanged();
 };
 
-inline GameDocument *NewTreeDocument()
+inline std::shared_ptr<GameDocument> NewTreeDocument()
 {
   const Game efg = NewTree();
   efg->SetTitle("Untitled Extensive Game");
   efg->NewPlayer("Player 1");
   efg->NewPlayer("Player 2");
-  return new GameDocument(efg);
+  return std::make_shared<GameDocument>(efg);
 }
 
-inline GameDocument *NewTableDocument(const std::vector<int> &p_dim)
+inline std::shared_ptr<GameDocument> NewTableDocument(const std::vector<int> &p_dim)
 {
   const Game nfg = NewTable(p_dim);
   nfg->SetTitle("Untitled Strategic Game");
@@ -364,15 +369,18 @@ inline GameDocument *NewTableDocument(const std::vector<int> &p_dim)
     labels[player->GetLabel()] = "Player " + std::to_string(pl++);
   }
   nfg->RelabelPlayers(labels);
-  return new GameDocument(nfg);
+  return std::make_shared<GameDocument>(nfg);
 }
 
 class GameView {
 protected:
-  GameDocument *m_doc;
+  std::shared_ptr<GameDocument> m_doc;
 
 public:
-  explicit GameView(GameDocument *p_doc) : m_doc(p_doc) { m_doc->AddView(this); }
+  explicit GameView(const std::shared_ptr<GameDocument> &p_doc) : m_doc(p_doc)
+  {
+    m_doc->AddView(this);
+  }
   virtual ~GameView() { m_doc->RemoveView(this); }
 
   virtual void OnUpdate() = 0;
@@ -380,7 +388,7 @@ class GameView {
   /// Post any pending changes in the viewer to the document
   virtual void PostPendingChanges() {}
 
-  GameDocument *GetDocument() const { return m_doc; }
+  std::shared_ptr<GameDocument> GetDocument() const { return m_doc; }
 };
 
 } // namespace Gambit::GUI
diff --git a/src/gui/gameframe.cc b/src/gui/gameframe.cc
index 0ca2531f4c..fd9de2b3d5 100644
--- a/src/gui/gameframe.cc
+++ b/src/gui/gameframe.cc
@@ -71,12 +71,12 @@ class ProfileListPanel final : public wxPanel, public GameView {
   void OnUpdate() override {}
 
 public:
-  ProfileListPanel(wxWindow *p_parent, GameDocument *p_doc);
+  ProfileListPanel(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc);
 
   void ShowMixed(bool p_show);
 };
 
-ProfileListPanel::ProfileListPanel(wxWindow *p_parent, GameDocument *p_doc)
+ProfileListPanel::ProfileListPanel(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc)
   : wxPanel(p_parent, wxID_ANY), GameView(p_doc)
 {
   auto *topSizer = new wxBoxSizer(wxHORIZONTAL);
@@ -124,12 +124,12 @@ class AnalysisNotebook final : public wxPanel, public GameView {
   void OnUpdate() override;
 
 public:
-  AnalysisNotebook(wxWindow *p_parent, GameDocument *p_doc);
+  AnalysisNotebook(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc);
 
   void ShowMixed(bool p_show);
 };
 
-AnalysisNotebook::AnalysisNotebook(wxWindow *p_parent, GameDocument *p_doc)
+AnalysisNotebook::AnalysisNotebook(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc)
   : wxPanel(p_parent, wxID_ANY), GameView(p_doc), m_profiles(new ProfileListPanel(this, p_doc))
 {
   m_choices = new wxChoice(this, wxID_ANY);
@@ -220,7 +220,7 @@ END_EVENT_TABLE()
 //               GameFrame: Constructor and destructor
 //---------------------------------------------------------------------
 
-GameFrame::GameFrame(wxWindow *p_parent, GameDocument *p_doc)
+GameFrame::GameFrame(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc)
   : wxFrame(p_parent, wxID_ANY, _T(""), wxDefaultPosition, wxDefaultSize), GameView(p_doc)
 {
   const wxRect area = wxGetClientDisplayRect();
@@ -1080,7 +1080,7 @@ void GameFrame::OnToolsDominance(wxCommandEvent &p_event)
   }
 }
 
-extern void ShowNashMonitorDialog(wxWindow *p_parent, GameDocument *p_doc,
+extern void ShowNashMonitorDialog(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc,
                                   const std::shared_ptr<AnalysisOutput> &p_command);
 
 void GameFrame::OnToolsEquilibrium(wxCommandEvent &)
@@ -1126,7 +1126,7 @@ void GameFrame::OnToolsEquilibrium(wxCommandEvent &)
   }
 }
 
-extern void LogitStrategic(wxWindow *, GameDocument *);
+extern void LogitStrategic(wxWindow *, const std::shared_ptr<GameDocument> &);
 
 void GameFrame::OnToolsQre(wxCommandEvent &)
 {
@@ -1169,7 +1169,7 @@ struct CloseWarningText {
   wxString secondary;
 };
 
-CloseWarningText CloseWarningMessage(GameDocument *p_doc)
+CloseWarningText CloseWarningMessage(const std::shared_ptr<GameDocument> &p_doc)
 {
   const bool gameModified = p_doc->IsGameModified();
   const bool workspaceModified = p_doc->IsWorkspaceModified();
diff --git a/src/gui/gameframe.h b/src/gui/gameframe.h
index 1c4131f851..8b0cc628a5 100644
--- a/src/gui/gameframe.h
+++ b/src/gui/gameframe.h
@@ -99,7 +99,7 @@ class GameFrame final : public wxFrame, public GameView {
 
 public:
   // CONSTRUCTOR AND DESTRUCTOR
-  GameFrame(wxWindow *p_parent, GameDocument *p_doc);
+  GameFrame(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc);
   ~GameFrame() override;
 
   DECLARE_EVENT_TABLE()
diff --git a/src/gui/nfgheadergrid.cc b/src/gui/nfgheadergrid.cc
index 15f979c6f9..7f324bbca6 100644
--- a/src/gui/nfgheadergrid.cc
+++ b/src/gui/nfgheadergrid.cc
@@ -271,7 +271,7 @@ int GetGlobalStrategyIndex(const GameStrategy &p_strategy)
   return index + p_strategy->GetNumber();
 }
 
-bool HasStrategyInfo(GameDocument *p_doc, const GameStrategy &p_strategy)
+bool HasStrategyInfo(const std::shared_ptr<GameDocument> &p_doc, const GameStrategy &p_strategy)
 {
   return !GetStrategyDescription(p_strategy).empty() ||
          p_doc->GetWorkspace().GetCurrentProfile() > 0;
@@ -291,7 +291,7 @@ class StrategyInfoPopup final : public wxPopupTransientWindow {
     BuildControls();
   }
 
-  void ShowForStrategy(GameDocument *p_doc, const GameStrategy &p_strategy,
+  void ShowForStrategy(const std::shared_ptr<GameDocument> &p_doc, const GameStrategy &p_strategy,
                        const wxPoint &p_anchor)
   {
     const wxString label = wxString::FromUTF8(p_strategy->GetLabel());
@@ -488,7 +488,7 @@ void RowPlayerGrid::OnHoverTimer(wxTimerEvent &)
   const int player = m_table->GetRowHeaderPlayer(m_hoverCol);
   const int strategy = m_table->GetRowHeaderStrategy(m_hoverCol, m_hoverRow);
   const auto gameStrategy = m_table->GetStrategyByPlayerAndIndex(player, strategy);
-  GameDocument *doc = m_table->GetDocument();
+  const std::shared_ptr<GameDocument> doc = m_table->GetDocument();
   if (!HasStrategyInfo(doc, gameStrategy)) {
     return;
   }
@@ -862,7 +862,7 @@ void ColPlayerGrid::OnHoverTimer(wxTimerEvent &)
   const int player = m_table->GetColHeaderPlayer(m_hoverRow);
   const int strategy = m_table->GetColHeaderStrategy(m_hoverRow, m_hoverCol);
   const auto gameStrategy = m_table->GetStrategyByPlayerAndIndex(player, strategy);
-  GameDocument *doc = m_table->GetDocument();
+  const std::shared_ptr<GameDocument> doc = m_table->GetDocument();
   if (!HasStrategyInfo(doc, gameStrategy)) {
     return;
   }
diff --git a/src/gui/nfgpanel.cc b/src/gui/nfgpanel.cc
index 0446c56a1a..3866b971f5 100644
--- a/src/gui/nfgpanel.cc
+++ b/src/gui/nfgpanel.cc
@@ -53,7 +53,7 @@ class StrategyDominanceToolbar final : public wxPanel, public GameView {
   void OnLastLevel(wxCommandEvent &);
 
 public:
-  StrategyDominanceToolbar(wxWindow *p_parent, GameDocument *p_doc);
+  StrategyDominanceToolbar(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc);
   ~StrategyDominanceToolbar() override = default;
 };
 
@@ -62,7 +62,8 @@ class StrategyDominanceToolbar final : public wxPanel, public GameView {
 #include "bitmaps/tobegin.xpm"
 #include "bitmaps/toend.xpm"
 
-StrategyDominanceToolbar::StrategyDominanceToolbar(wxWindow *p_parent, GameDocument *p_doc)
+StrategyDominanceToolbar::StrategyDominanceToolbar(wxWindow *p_parent,
+                                                   const std::shared_ptr<GameDocument> &p_doc)
   : wxPanel(p_parent, wxID_ANY), GameView(p_doc)
 {
   auto *topSizer = new wxBoxSizer(wxHORIZONTAL);
@@ -160,7 +161,8 @@ BEGIN_EVENT_TABLE(NfgPanel, wxPanel)
 EVT_MENU(GBT_MENU_TOOLS_DOMINANCE, NfgPanel::OnToolsDominance)
 END_EVENT_TABLE()
 
-NfgPanel::NfgPanel(wxWindow *p_parent, GameDocument *p_doc, bool p_showDominance)
+NfgPanel::NfgPanel(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc,
+                   bool p_showDominance)
   : wxPanel(p_parent, wxID_ANY), GameView(p_doc),
     m_dominanceToolbar(new StrategyDominanceToolbar(this, m_doc)),
     m_tableWidget(new TableWidget(this, wxID_ANY, m_doc))
diff --git a/src/gui/nfgpanel.h b/src/gui/nfgpanel.h
index d97209989c..d6e4c359ea 100644
--- a/src/gui/nfgpanel.h
+++ b/src/gui/nfgpanel.h
@@ -35,7 +35,7 @@ class NfgPanel final : public wxPanel, public GameView {
   void OnToolsDominance(wxCommandEvent &);
 
 public:
-  NfgPanel(wxWindow *p_parent, GameDocument *p_doc, bool p_showDominance);
+  NfgPanel(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc, bool p_showDominance);
   ~NfgPanel() override = default;
 
   bool IsDominanceShown() const { return m_dominanceToolbar->IsShown(); }
diff --git a/src/gui/nfgprofile.cc b/src/gui/nfgprofile.cc
index 1a83908c5e..855b8990fd 100644
--- a/src/gui/nfgprofile.cc
+++ b/src/gui/nfgprofile.cc
@@ -32,7 +32,8 @@ namespace Gambit::GUI {
 //              class MixedProfileList: Member functions
 //-------------------------------------------------------------------------
 
-MixedStrategyProfileList::MixedStrategyProfileList(wxWindow *p_parent, GameDocument *p_doc)
+MixedStrategyProfileList::MixedStrategyProfileList(wxWindow *p_parent,
+                                                   const std::shared_ptr<GameDocument> &p_doc)
   : wxGrid(p_parent, wxID_ANY), GameView(p_doc)
 {
   CreateGrid(0, 0);
@@ -78,7 +79,7 @@ void MixedStrategyProfileList::OnSelectCell(wxGridEvent &p_event)
 }
 
 #ifdef UNUSED
-static Gambit::GameStrategy GetStrategy(GameDocument *p_doc, int p_index)
+static Gambit::GameStrategy GetStrategy(const std::shared_ptr<GameDocument> &p_doc, int p_index)
 {
   int index = 0;
   for (int pl = 1; pl <= p_doc->GetGame()->NumPlayers(); pl++) {
@@ -93,7 +94,7 @@ static Gambit::GameStrategy GetStrategy(GameDocument *p_doc, int p_index)
 }
 #endif
 
-static wxColour GetPlayerColor(const GameDocument *p_doc, int p_index)
+static wxColour GetPlayerColor(const std::shared_ptr<GameDocument> &p_doc, int p_index)
 {
   int index = 0;
   for (const auto &player : p_doc->GetGame()->GetPlayers()) {
diff --git a/src/gui/nfgprofile.h b/src/gui/nfgprofile.h
index c9029460c0..76d708ea7f 100644
--- a/src/gui/nfgprofile.h
+++ b/src/gui/nfgprofile.h
@@ -42,7 +42,7 @@ class MixedStrategyProfileList final : public wxGrid, public GameView {
   void OnUpdate() override;
 
 public:
-  MixedStrategyProfileList(wxWindow *p_parent, GameDocument *p_doc);
+  MixedStrategyProfileList(wxWindow *p_parent, const std::shared_ptr<GameDocument> &p_doc);
   ~MixedStrategyProfileList() override;
 };
 } // namespace Gambit::GUI
diff --git a/src/gui/nfgtable.cc b/src/gui/nfgtable.cc
index 6406a6ac99..f8747eb098 100644
--- a/src/gui/nfgtable.cc
+++ b/src/gui/nfgtable.cc
@@ -93,7 +93,8 @@ bool TableWidget::IsColHeaderStrategyDominated(int headerRow, int headerCol, boo
   return support.IsDominated(GetStrategyByPlayerAndIndex(player, strat), strict);
 }
 
-TableWidget::TableWidget(NfgPanel *p_parent, wxWindowID p_id, GameDocument *p_doc)
+TableWidget::TableWidget(NfgPanel *p_parent, wxWindowID p_id,
+                         const std::shared_ptr<GameDocument> &p_doc)
   : wxPanel(p_parent, p_id), m_doc(p_doc), m_nfgPanel(p_parent), m_payoffGrid(nullptr),
     m_rowGrid(nullptr), m_colGrid(nullptr), m_layout(std::make_shared<StrategicTableLayout>(p_doc))
 {
diff --git a/src/gui/nfgtable.h b/src/gui/nfgtable.h
index 11a9a954bf..28a6ff7f08 100644
--- a/src/gui/nfgtable.h
+++ b/src/gui/nfgtable.h
@@ -76,7 +76,7 @@ class TableGridBase : public wxGrid {
 };
 
 class StrategicTableLayout {
-  GameDocument *m_doc;
+  std::shared_ptr<GameDocument> m_doc;
   std::vector<int> m_rowPlayers;
   std::vector<int> m_colPlayers;
 
@@ -93,7 +93,7 @@ class StrategicTableLayout {
   }
 
 public:
-  explicit StrategicTableLayout(GameDocument *doc) : m_doc(doc)
+  explicit StrategicTableLayout(const std::shared_ptr<GameDocument> &doc) : m_doc(doc)
   {
     if (m_doc->GetGame()->NumPlayers() >= 1) {
       m_rowPlayers.push_back(1);
@@ -106,7 +106,7 @@ class StrategicTableLayout {
     }
   }
 
-  GameDocument *GetDocument() const { return m_doc; }
+  std::shared_ptr<GameDocument> GetDocument() const { return m_doc; }
 
   /// Returns the number of players assigned to the rows
   int NumRowPlayers() const { return m_rowPlayers.size(); }
@@ -283,7 +283,7 @@ class StrategicTableLayout {
 //! the display of row and column labels
 //!
 class TableWidget final : public wxPanel {
-  GameDocument *m_doc;
+  std::shared_ptr<GameDocument> m_doc;
   NfgPanel *m_nfgPanel;
   wxGrid *m_payoffGrid, *m_rowGrid, *m_colGrid;
 
@@ -341,7 +341,7 @@ class TableWidget final : public wxPanel {
   void SyncScrollFromPayoff();
 
 public:
-  TableWidget(NfgPanel *p_parent, wxWindowID p_id, GameDocument *p_doc);
+  TableWidget(NfgPanel *p_parent, wxWindowID p_id, const std::shared_ptr<GameDocument> &p_doc);
 
   /// @name Coordination of grids
   //@{
@@ -454,7 +454,7 @@ class TableWidget final : public wxPanel {
   bool IsReadOnly() const;
   wxColour GetPlayerColor(int player) const;
   const StrategySupportProfile &GetSupport() const { return m_doc->GetNfgSupport(); }
-  GameDocument *GetDocument() const { return m_doc; }
+  std::shared_ptr<GameDocument> GetDocument() const { return m_doc; }
 
   bool IsRowHeaderStrategyDominated(int headerCol, int headerRow, bool strict) const;
   bool IsColHeaderStrategyDominated(int headerRow, int headerCol, bool strict) const;