Fix f6d5c01: Delay deletion when closing windows

35 files changed, 231 insertions, 166 deletions

diff --git a/src/ai/ai_gui.cpp b/src/ai/ai_gui.cpp
index 49e37621e..1817148f4 100644
--- a/src/ai/ai_gui.cpp
+++ b/src/ai/ai_gui.cpp
@@ -196,7 +196,7 @@ struct AIListWindow : public Window {
 					this->SetDirty();
 					if (click_count > 1) {
 						this->ChangeAI();
-						delete this;
+						this->Close();
 					}
 				}
 				break;
@@ -204,12 +204,12 @@ struct AIListWindow : public Window {
 
 			case WID_AIL_ACCEPT: {
 				this->ChangeAI();
-				delete this;
+				this->Close();
 				break;
 			}
 
 			case WID_AIL_CANCEL:
-				delete this;
+				this->Close();
 				break;
 		}
 	}
@@ -227,7 +227,7 @@ struct AIListWindow : public Window {
 	void OnInvalidateData(int data = 0, bool gui_scope = true) override
 	{
 		if (_game_mode == GM_NORMAL && Company::IsValidID(this->slot)) {
-			delete this;
+			this->Close();
 			return;
 		}
 
@@ -518,7 +518,7 @@ struct AISettingsWindow : public Window {
 			}
 
 			case WID_AIS_ACCEPT:
-				delete this;
+				this->Close();
 				break;
 
 			case WID_AIS_RESET:
@@ -655,7 +655,7 @@ struct ScriptTextfileWindow : public TextfileWindow {
 	{
 		const char *textfile = GetConfig(slot)->GetTextfile(file_type, slot);
 		if (textfile == nullptr) {
-			delete this;
+			this->Close();
 		} else {
 			this->LoadTextfile(textfile, (slot == OWNER_DEITY) ? GAME_DIR : AI_DIR);
 		}
@@ -744,10 +744,11 @@ struct AIConfigWindow : public Window {
 		this->OnInvalidateData(0);
 	}
 
-	~AIConfigWindow()
+	void Close() override
 	{
 		DeleteWindowByClass(WC_AI_LIST);
 		DeleteWindowByClass(WC_AI_SETTINGS);
+		this->Window::Close();
 	}
 
 	void SetStringParameters(int widget) const override
@@ -929,7 +930,7 @@ struct AIConfigWindow : public Window {
 				break;
 
 			case WID_AIC_CLOSE:
-				delete this;
+				this->Close();
 				break;
 
 			case WID_AIC_CONTENT_DOWNLOAD:
diff --git a/src/airport_gui.cpp b/src/airport_gui.cpp
index 7eb8c6dce..1941a8602 100644
--- a/src/airport_gui.cpp
+++ b/src/airport_gui.cpp
@@ -76,10 +76,11 @@ struct BuildAirToolbarWindow : Window {
 		this->last_user_action = WIDGET_LIST_END;
 	}
 
-	~BuildAirToolbarWindow()
+	void Close() override
 	{
 		if (this->IsWidgetLowered(WID_AT_AIRPORT)) SetViewportCatchmentStation(nullptr, true);
 		if (_settings_client.gui.link_terraform_toolbar) DeleteWindowById(WC_SCEN_LAND_GEN, 0, false);
+		this->Window::Close();
 	}
 
 	/**
@@ -276,9 +277,10 @@ public:
 		if (selectFirstAirport) this->SelectFirstAvailableAirport(true);
 	}
 
-	virtual ~BuildAirportWindow()
+	void Close() override
 	{
 		DeleteWindowById(WC_SELECT_STATION, 0);
+		this->PickerWindowBase::Close();
 	}
 
 	void SetStringParameters(int widget) const override
diff --git a/src/bootstrap_gui.cpp b/src/bootstrap_gui.cpp
index 7495e08ba..d8e4aedec 100644
--- a/src/bootstrap_gui.cpp
+++ b/src/bootstrap_gui.cpp
@@ -91,9 +91,10 @@ public:
 		this->InitNested(1);
 	}
 
-	~BootstrapErrorWindow()
+	void Close() override
 	{
 		_exit_game = true;
+		this->Window::Close();
 	}
 
 	void UpdateWidgetSize(int widget, Dimension *size, const Dimension &padding, Dimension *fill, Dimension *resize) override
@@ -144,12 +145,13 @@ public:
 	{
 	}
 
-	~BootstrapContentDownloadStatusWindow()
+	void Close() override
 	{
 		/* If we are not set to exit the game, it means the bootstrap failed. */
 		if (!_exit_game) {
 			new BootstrapErrorWindow();
 		}
+		this->BaseNetworkContentDownloadStatusWindow::Close();
 	}
 
 	void OnDownloadComplete(ContentID cid) override
@@ -162,7 +164,7 @@ public:
 
 		/* _exit_game is used to break out of the outer video driver's MainLoop. */
 		_exit_game = true;
-		delete this;
+		this->Close();
 	}
 };
 
@@ -201,9 +203,10 @@ public:
 	}
 
 	/** Stop listening to the content client events. */
-	~BootstrapAskForDownloadWindow()
+	void Close() override
 	{
 		_network_content_client.RemoveCallback(this);
+		this->Window::Close();
 	}
 
 	void UpdateWidgetSize(int widget, Dimension *size, const Dimension &padding, Dimension *fill, Dimension *resize) override
@@ -264,7 +267,7 @@ public:
 		/* And once the meta data is received, start downloading it. */
 		_network_content_client.Select(ci->id);
 		new BootstrapContentDownloadStatusWindow();
-		delete this;
+		this->Close();
 	}
 };
 
diff --git a/src/bridge_gui.cpp b/src/bridge_gui.cpp
index 07858e7af..4a9a56b79 100644
--- a/src/bridge_gui.cpp
+++ b/src/bridge_gui.cpp
@@ -249,7 +249,7 @@ public:
 		if (i < 9 && i < this->bridges->size()) {
 			/* Build the requested bridge */
 			this->BuildBridge(i);
-			delete this;
+			this->Close();
 			return ES_HANDLED;
 		}
 		return ES_NOT_HANDLED;
@@ -263,7 +263,7 @@ public:
 				uint i = this->vscroll->GetScrolledRowFromWidget(pt.y, this, WID_BBS_BRIDGE_LIST);
 				if (i < this->bridges->size()) {
 					this->BuildBridge(i);
-					delete this;
+					this->Close();
 				}
 				break;
 			}
diff --git a/src/company_gui.cpp b/src/company_gui.cpp
index a23bda7bd..fe8c2326c 100644
--- a/src/company_gui.cpp
+++ b/src/company_gui.cpp
@@ -1586,7 +1586,7 @@ public:
 
 			/* Cancel button */
 			case WID_SCMF_CANCEL:
-				delete this;
+				this->Close();
 				break;
 
 			/* Load button */
@@ -2767,7 +2767,7 @@ struct BuyCompanyWindow : Window {
 	{
 		switch (widget) {
 			case WID_BC_NO:
-				delete this;
+				this->Close();
 				break;
 
 			case WID_BC_YES:
diff --git a/src/console_gui.cpp b/src/console_gui.cpp
index 731073866..e5d80fcba 100644
--- a/src/console_gui.cpp
+++ b/src/console_gui.cpp
@@ -185,10 +185,11 @@ struct IConsoleWindow : Window
 		ResizeWindow(this, _screen.width, _screen.height / 3);
 	}
 
-	~IConsoleWindow()
+	void Close() override
 	{
 		_iconsole_mode = ICONSOLE_CLOSED;
 		VideoDriver::GetInstance()->EditBoxLostFocus();
+		this->Window::Close();
 	}
 
 	/**
diff --git a/src/date_gui.cpp b/src/date_gui.cpp
index 8feb3f8ad..77b9a7c4c 100644
--- a/src/date_gui.cpp
+++ b/src/date_gui.cpp
@@ -147,7 +147,7 @@ struct SetDateWindow : Window {
 
 			case WID_SD_SET_DATE:
 				if (this->callback != nullptr) this->callback(this, ConvertYMDToDate(this->date.year, this->date.month, this->date.day));
-				delete this;
+				this->Close();
 				break;
 		}
 	}
diff --git a/src/depot_gui.cpp b/src/depot_gui.cpp
index 0756eae2c..80774e900 100644
--- a/src/depot_gui.cpp
+++ b/src/depot_gui.cpp
@@ -291,11 +291,12 @@ struct DepotWindow : Window {
 		OrderBackup::Reset();
 	}
 
-	~DepotWindow()
+	void Close() override
 	{
 		DeleteWindowById(WC_BUILD_VEHICLE, this->window_number);
 		DeleteWindowById(GetWindowClassForVehicleType(this->type), VehicleListIdentifier(VL_DEPOT_LIST, this->type, this->owner, this->GetDepotIndex()).Pack(), false);
 		OrderBackup::Reset(this->window_number);
+		this->Window::Close();
 	}
 
 	/**
diff --git a/src/dock_gui.cpp b/src/dock_gui.cpp
index 850b9d3f3..483a71d6b 100644
--- a/src/dock_gui.cpp
+++ b/src/dock_gui.cpp
@@ -101,10 +101,11 @@ struct BuildDocksToolbarWindow : Window {
 		if (_settings_client.gui.link_terraform_toolbar) ShowTerraformToolbar(this);
 	}
 
-	~BuildDocksToolbarWindow()
+	void Close() override
 	{
 		if (_game_mode == GM_NORMAL && this->IsWidgetLowered(WID_DT_STATION)) SetViewportCatchmentStation(nullptr, true);
 		if (_settings_client.gui.link_terraform_toolbar) DeleteWindowById(WC_SCEN_LAND_GEN, 0, false);
+		this->Window::Close();
 	}
 
 	/**
@@ -416,9 +417,10 @@ public:
 		this->LowerWidget(_settings_client.gui.station_show_coverage + BDSW_LT_OFF);
 	}
 
-	virtual ~BuildDocksStationWindow()
+	void Close() override
 	{
 		DeleteWindowById(WC_SELECT_STATION, 0);
+		this->PickerWindowBase::Close();
 	}
 
 	void OnPaint() override
diff --git a/src/engine_gui.cpp b/src/engine_gui.cpp
index 77ce95413..bc0143be1 100644
--- a/src/engine_gui.cpp
+++ b/src/engine_gui.cpp
@@ -128,7 +128,7 @@ struct EnginePreviewWindow : Window {
 				DoCommandP(0, this->window_number, 0, CMD_WANT_ENGINE_PREVIEW);
 				FALLTHROUGH;
 			case WID_EP_NO:
-				if (!_shift_pressed) delete this;
+				if (!_shift_pressed) this->Close();
 				break;
 		}
 	}
@@ -138,7 +138,7 @@ struct EnginePreviewWindow : Window {
 		if (!gui_scope) return;
 
 		EngineID engine = this->window_number;
-		if (Engine::Get(engine)->preview_company != _local_company) delete this;
+		if (Engine::Get(engine)->preview_company != _local_company) this->Close();
 	}
 };
 
diff --git a/src/error_gui.cpp b/src/error_gui.cpp
index 7b7413228..70b403a68 100644
--- a/src/error_gui.cpp
+++ b/src/error_gui.cpp
@@ -250,7 +250,7 @@ public:
 	void OnInvalidateData(int data = 0, bool gui_scope = true) override
 	{
 		/* If company gets shut down, while displaying an error about it, remove the error message. */
-		if (this->face != INVALID_COMPANY && !Company::IsValidID(this->face)) delete this;
+		if (this->face != INVALID_COMPANY && !Company::IsValidID(this->face)) this->Close();
 	}
 
 	void SetStringParameters(int widget) const override
@@ -298,20 +298,21 @@ public:
 	void OnMouseLoop() override
 	{
 		/* Disallow closing the window too easily, if timeout is disabled */
-		if (_right_button_down && !this->display_timer.HasElapsed()) delete this;
+		if (_right_button_down && !this->display_timer.HasElapsed()) this->Close();
 	}
 
 	void OnRealtimeTick(uint delta_ms) override
 	{
 		if (this->display_timer.CountElapsed(delta_ms) == 0) return;
 
-		delete this;
+		this->Close();
 	}
 
-	~ErrmsgWindow()
+	void Close() override
 	{
 		SetRedErrorSquare(INVALID_TILE);
 		if (_window_system_initialized) ShowFirstError();
+		this->Window::Close();
 	}
 
 	/**
@@ -354,7 +355,7 @@ void UnshowCriticalError()
 	if (_window_system_initialized && w != nullptr) {
 		if (w->IsCritical()) _error_list.push_front(*w);
 		_window_system_initialized = false;
-		delete w;
+		w->Close();
 	}
 }
 
@@ -403,18 +404,20 @@ void ShowErrorMessage(StringID summary_msg, StringID detailed_msg, WarningLevel
 	data.CopyOutDParams();
 
 	ErrmsgWindow *w = (ErrmsgWindow*)FindWindowById(WC_ERRMSG, 0);
-	if (w != nullptr && w->IsCritical()) {
-		/* A critical error is currently shown. */
-		if (wl == WL_CRITICAL) {
-			/* Push another critical error in the queue of errors,
-			 * but do not put other errors in the queue. */
-			_error_list.push_back(data);
+	if (w != nullptr) {
+		if (w->IsCritical()) {
+			/* A critical error is currently shown. */
+			if (wl == WL_CRITICAL) {
+				/* Push another critical error in the queue of errors,
+				 * but do not put other errors in the queue. */
+				_error_list.push_back(data);
+			}
+			return;
 		}
-	} else {
-		/* Nothing or a non-critical error was shown. */
-		delete w;
-		new ErrmsgWindow(data);
+		/* A non-critical error was shown. */
+		w->Close();
 	}
+	new ErrmsgWindow(data);
 }
 
 
@@ -425,7 +428,7 @@ void ShowErrorMessage(StringID summary_msg, StringID detailed_msg, WarningLevel
 bool HideActiveErrorMessage() {
 	ErrmsgWindow *w = (ErrmsgWindow*)FindWindowById(WC_ERRMSG, 0);
 	if (w == nullptr) return false;
-	delete w;
+	w->Close();
 	return true;
 }
 
diff --git a/src/fios_gui.cpp b/src/fios_gui.cpp
index 40a082d64..c04092f6b 100644
--- a/src/fios_gui.cpp
+++ b/src/fios_gui.cpp
@@ -398,12 +398,13 @@ public:
 		}
 	}
 
-	virtual ~SaveLoadWindow()
+	void Close() override
 	{
 		/* pause is only used in single-player, non-editor mode, non menu mode */
 		if (!_networking && _game_mode != GM_EDITOR && _game_mode != GM_MENU) {
 			DoCommandP(0, PM_PAUSED_SAVELOAD, 0, CMD_PAUSE);
 		}
+		this->Window::Close();
 	}
 
 	void DrawWidget(const Rect &r, int widget) const override
@@ -617,12 +618,12 @@ public:
 				_file_to_saveload.SetTitle(this->selected->title);
 
 				if (this->abstract_filetype == FT_HEIGHTMAP) {
-					delete this;
+					this->Close();
 					ShowHeightmapLoad();
 				} else if (!_load_check_data.HasNewGrfs() || _load_check_data.grf_compatibility != GLC_NOT_FOUND || _settings_client.gui.UserIsAllowedToChangeNewGRFs()) {
 					_switch_mode = (_game_mode == GM_EDITOR) ? SM_LOAD_SCENARIO : SM_LOAD_GAME;
 					ClearErrorMessages();
-					delete this;
+					this->Close();
 				}
 				break;
 			}
@@ -688,7 +689,7 @@ public:
 							_file_to_saveload.SetName(name);
 							_file_to_saveload.SetTitle(file->title);
 
-							delete this;
+							this->Close();
 							ShowHeightmapLoad();
 						}
 					}
@@ -749,7 +750,7 @@ public:
 	EventState OnKeyPress(WChar key, uint16 keycode) override
 	{
 		if (keycode == WKC_ESC) {
-			delete this;
+			this->Close();
 			return ES_HANDLED;
 		}
 
diff --git a/src/goal_gui.cpp b/src/goal_gui.cpp
index 9fdca309b..922f5f5d5 100644
--- a/src/goal_gui.cpp
+++ b/src/goal_gui.cpp
@@ -384,17 +384,17 @@ struct GoalQuestionWindow : public Window {
 		switch (widget) {
 			case WID_GQ_BUTTON_1:
 				DoCommandP(0, this->window_number, this->button[0], CMD_GOAL_QUESTION_ANSWER);
-				delete this;
+				this->Close();
 				break;
 
 			case WID_GQ_BUTTON_2:
 				DoCommandP(0, this->window_number, this->button[1], CMD_GOAL_QUESTION_ANSWER);
-				delete this;
+				this->Close();
 				break;
 
 			case WID_GQ_BUTTON_3:
 				DoCommandP(0, this->window_number, this->button[2], CMD_GOAL_QUESTION_ANSWER);
-				delete this;
+				this->Close();
 				break;
 		}
 	}
diff --git a/src/highscore_gui.cpp b/src/highscore_gui.cpp
index 356235fa0..e36935c1e 100644
--- a/src/highscore_gui.cpp
+++ b/src/highscore_gui.cpp
@@ -64,7 +64,7 @@ struct EndGameHighScoreBaseWindow : Window {
 
 	void OnClick(Point pt, int widget, int click_count) override
 	{
-		delete this;
+		this->Close();
 	}
 
 	EventState OnKeyPress(WChar key, uint16 keycode) override
@@ -79,7 +79,7 @@ struct EndGameHighScoreBaseWindow : Window {
 			case WKC_RETURN:
 			case WKC_ESC:
 			case WKC_SPACE:
-				delete this;
+				this->Close();
 				return ES_HANDLED;
 
 			default:
@@ -122,10 +122,11 @@ struct EndGameWindow : EndGameHighScoreBaseWindow {
 		MarkWholeScreenDirty();
 	}
 
-	~EndGameWindow()
+	void Close() override
 	{
 		if (!_networking) DoCommandP(0, PM_PAUSED_NORMAL, 0, CMD_PAUSE); // unpause
 		ShowHighscoreTable(this->window_number, this->rank);
+		this->EndGameHighScoreBaseWindow::Close();
 	}
 
 	void OnPaint() override
@@ -169,11 +170,13 @@ struct HighScoreWindow : EndGameHighScoreBaseWindow {
 		this->rank = ranking;
 	}
 
-	~HighScoreWindow()
+	void Close() override
 	{
 		if (_game_mode != GM_MENU) ShowVitalWindows();
 
 		if (!_networking && !this->game_paused_by_player) DoCommandP(0, PM_PAUSED_NORMAL, 0, CMD_PAUSE); // unpause
+
+		this->EndGameHighScoreBaseWindow::Close();
 	}
 
 	void OnPaint() override
diff --git a/src/misc_gui.cpp b/src/misc_gui.cpp
index f7061d328..59b0282d5 100644
--- a/src/misc_gui.cpp
+++ b/src/misc_gui.cpp
@@ -759,20 +759,20 @@ struct TooltipsWindow : public Window
 	{
 		/* Always close tooltips when the cursor is not in our window. */
 		if (!_cursor.in_window) {
-			delete this;
+			this->Close();
 			return;
 		}
 
 		/* We can show tooltips while dragging tools. These are shown as long as
 		 * we are dragging the tool. Normal tooltips work with hover or rmb. */
 		switch (this->close_cond) {
-			case TCC_RIGHT_CLICK: if (!_right_button_down) delete this; break;
-			case TCC_HOVER: if (!_mouse_hovering) delete this; break;
+			case TCC_RIGHT_CLICK: if (!_right_button_down) this->Close(); break;
+			case TCC_HOVER: if (!_mouse_hovering) this->Close(); break;
 			case TCC_NONE: break;
 
 			case TCC_EXIT_VIEWPORT: {
 				Window *w = FindWindowFromPt(_cursor.pos.x, _cursor.pos.y);
-				if (w == nullptr || IsPtInWindowViewport(w, _cursor.pos.x, _cursor.pos.y) == nullptr) delete this;
+				if (w == nullptr || IsPtInWindowViewport(w, _cursor.pos.x, _cursor.pos.y) == nullptr) this->Close();
 				break;
 			}
 		}
@@ -1090,18 +1090,19 @@ struct QueryStringWindow : public Window
 				FALLTHROUGH;
 
 			case WID_QS_CANCEL:
-				delete this;
+				this->Close();
 				break;
 		}
 	}
 
-	~QueryStringWindow()
+	void Close() override
 	{
 		if (!this->editbox.handled && this->parent != nullptr) {
 			Window *parent = this->parent;
-			this->parent = nullptr; // so parent doesn't try to delete us again
+			this->parent = nullptr; // so parent doesn't try to close us again
 			parent->OnQueryTextFinished(nullptr);
 		}
+		this->Window::Close();
 	}
 };
 
@@ -1167,9 +1168,10 @@ struct QueryWindow : public Window {
 		this->InitNested(WN_CONFIRM_POPUP_QUERY);
 	}
 
-	~QueryWindow()
+	void Close() override
 	{
 		if (this->proc != nullptr) this->proc(this->parent, false);
+		this->Window::Close();
 	}
 
 	void FindWindowPlacementAndResize(int def_width, int def_height) override
@@ -1222,7 +1224,7 @@ struct QueryWindow : public Window {
 				Window *parent = this->parent;
 				/* Prevent the destructor calling the callback function */
 				this->proc = nullptr;
-				delete this;
+				this->Close();
 				if (proc != nullptr) {
 					proc(parent, true);
 					proc = nullptr;
@@ -1230,7 +1232,7 @@ struct QueryWindow : public Window {
 				break;
 			}
 			case WID_Q_NO:
-				delete this;
+				this->Close();
 				break;
 		}
 	}
@@ -1248,7 +1250,7 @@ struct QueryWindow : public Window {
 				FALLTHROUGH;
 
 			case WKC_ESC:
-				delete this;
+				this->Close();
 				return ES_HANDLED;
 		}
 		return ES_NOT_HANDLED;
@@ -1289,13 +1291,13 @@ void ShowQuery(StringID caption, StringID message, Window *parent, QueryCallback
 {
 	if (parent == nullptr) parent = FindWindowById(WC_MAIN_WINDOW, 0);
 
-	for (const Window *w : Window::Iterate()) {
+	for (Window *w : Window::Iterate()) {
 		if (w->window_class != WC_CONFIRM_POPUP_QUERY) continue;
 
-		const QueryWindow *qw = (const QueryWindow *)w;
+		QueryWindow *qw = dynamic_cast<QueryWindow *>(w);
 		if (qw->parent != parent || qw->proc != callback) continue;
 
-		delete qw;
+		qw->Close();
 		break;
 	}
 
diff --git a/src/network/network_chat_gui.cpp b/src/network/network_chat_gui.cpp
index 068a5314e..53546aa87 100644
--- a/src/network/network_chat_gui.cpp
+++ b/src/network/network_chat_gui.cpp
@@ -307,9 +307,10 @@ struct NetworkChatWindow : public Window {
 		PositionNetworkChatWindow(this);
 	}
 
-	~NetworkChatWindow()
+	void Close() override
 	{
 		InvalidateWindowData(WC_NEWS_WINDOW, 0, 0);
+		this->Window::Close();
 	}
 
 	void FindWindowPlacementAndResize(int def_width, int def_height) override
@@ -470,7 +471,7 @@ struct NetworkChatWindow : public Window {
 				FALLTHROUGH;
 
 			case WID_NC_CLOSE: /* Cancel */
-				delete this;
+				this->Close();
 				break;
 		}
 	}
@@ -497,7 +498,7 @@ struct NetworkChatWindow : public Window {
 	 */
 	void OnInvalidateData(int data = 0, bool gui_scope = true) override
 	{
-		if (data == this->dest) delete this;
+		if (data == this->dest) this->Close();
 	}
 };
 
diff --git a/src/network/network_content_gui.cpp b/src/network/network_content_gui.cpp
index dd9590e99..8c75cb572 100644
--- a/src/network/network_content_gui.cpp
+++ b/src/network/network_content_gui.cpp
@@ -109,9 +109,10 @@ BaseNetworkContentDownloadStatusWindow::BaseNetworkContentDownloadStatusWindow(W
 	this->InitNested(WN_NETWORK_STATUS_WINDOW_CONTENT_DOWNLOAD);
 }
 
-BaseNetworkContentDownloadStatusWindow::~BaseNetworkContentDownloadStatusWindow()
+void BaseNetworkContentDownloadStatusWindow::Close()
 {
 	_network_content_client.RemoveCallback(this);
+	this->Window::Close();
 }
 
 void BaseNetworkContentDownloadStatusWindow::DrawWidget(const Rect &r, int widget) const
@@ -171,8 +172,7 @@ public:
 		this->parent = FindWindowById(WC_NETWORK_WINDOW, WN_NETWORK_WINDOW_CONTENT_LIST);
 	}
 
-	/** Free whatever we've allocated */
-	~NetworkContentDownloadStatusWindow()
+	void Close() override
 	{
 		TarScanner::Mode mode = TarScanner::NONE;
 		for (auto ctype : this->receivedTypes) {
@@ -254,6 +254,8 @@ public:
 
 		/* Always invalidate the download window; tell it we are going to be gone */
 		InvalidateWindowData(WC_NETWORK_WINDOW, WN_NETWORK_WINDOW_CONTENT_LIST, 2);
+
+		this->BaseNetworkContentDownloadStatusWindow::Close();
 	}
 
 	void OnClick(Point pt, int widget, int click_count) override
@@ -261,7 +263,7 @@ public:
 		if (widget == WID_NCDS_CANCELOK) {
 			if (this->downloaded_bytes != this->total_bytes) {
 				_network_content_client.CloseConnection();
-				delete this;
+				this->Close();
 			} else {
 				/* If downloading succeeded, close the online content window. This will close
 				 * the current window as well. */
@@ -549,10 +551,10 @@ public:
 		this->InvalidateData();
 	}
 
-	/** Free everything we allocated */
-	~NetworkContentListWindow()
+	void Close() override
 	{
 		_network_content_client.RemoveCallback(this);
+		this->Window::Close();
 	}
 
 	void UpdateWidgetSize(int widget, Dimension *size, const Dimension &padding, Dimension *fill, Dimension *resize) override
@@ -837,7 +839,7 @@ public:
 				break;
 
 			case WID_NCL_CANCEL:
-				delete this;
+				this->Close();
 				break;
 
 			case WID_NCL_OPEN_URL:
@@ -941,7 +943,7 @@ public:
 	{
 		if (!success) {
 			ShowErrorMessage(STR_CONTENT_ERROR_COULD_NOT_CONNECT, INVALID_STRING_ID, WL_ERROR);
-			delete this;
+			this->Close();
 			return;
 		}
 
diff --git a/src/network/network_content_gui.h b/src/network/network_content_gui.h
index 4853101bb..dd9d9cfdf 100644
--- a/src/network/network_content_gui.h
+++ b/src/network/network_content_gui.h
@@ -32,11 +32,7 @@ public:
 	 */
 	BaseNetworkContentDownloadStatusWindow(WindowDesc *desc);
 
-	/**
-	 * Free everything associated with this window.
-	 */
-	~BaseNetworkContentDownloadStatusWindow();
-
+	void Close() override;
 	void DrawWidget(const Rect &r, int widget) const override;
 	void OnDownloadProgress(const ContentInfo *ci, int bytes) override;
 };
diff --git a/src/network/network_gui.cpp b/src/network/network_gui.cpp
index 322e128cf..7f179a05f 100644
--- a/src/network/network_gui.cpp
+++ b/src/network/network_gui.cpp
@@ -2597,7 +2597,7 @@ struct NetworkCompanyPasswordWindow : public Window {
 				FALLTHROUGH;
 
 			case WID_NCP_CANCEL:
-				delete this;
+				this->Close();
 				break;
 
 			case WID_NCP_SAVE_AS_DEFAULT_PASSWORD:
diff --git a/src/newgrf_gui.cpp b/src/newgrf_gui.cpp
index 9e86a575f..a9b43ea9d 100644
--- a/src/newgrf_gui.cpp
+++ b/src/newgrf_gui.cpp
@@ -424,7 +424,7 @@ struct NewGRFParametersWindow : public Window {
 				break;
 
 			case WID_NP_ACCEPT:
-				delete this;
+				this->Close();
 				break;
 		}
 	}
@@ -662,7 +662,7 @@ struct NewGRFWindow : public Window, NewGRFScanCallback {
 		this->OnInvalidateData(GOID_NEWGRF_CURRENT_LOADED);
 	}
 
-	~NewGRFWindow()
+	void Close() override
 	{
 		DeleteWindowByClass(WC_GRF_PARAMETERS);
 		DeleteWindowByClass(WC_TEXTFILE);
@@ -674,6 +674,11 @@ struct NewGRFWindow : public Window, NewGRFScanCallback {
 			ReloadNewGRFData();
 		}
 
+		this->Window::Close();
+	}
+
+	~NewGRFWindow()
+	{
 		/* Remove the temporary copy of grf-list used in window */
 		ClearGRFConfigList(&this->actives);
 	}
@@ -2121,13 +2126,13 @@ struct SavePresetWindow : public Window {
 			}
 
 			case WID_SVP_CANCEL:
-				delete this;
+				this->Close();
 				break;
 
 			case WID_SVP_SAVE: {
 				Window *w = FindWindowById(WC_GAME_OPTIONS, WN_GAME_OPTIONS_NEWGRF_STATE);
 				if (w != nullptr && !StrEmpty(this->presetname_editbox.text.buf)) w->OnQueryTextFinished(this->presetname_editbox.text.buf);
-				delete this;
+				this->Close();
 				break;
 			}
 		}
diff --git a/src/news_gui.cpp b/src/news_gui.cpp
index 8dc66c846..513624b3e 100644
--- a/src/news_gui.cpp
+++ b/src/news_gui.cpp
@@ -479,7 +479,7 @@ struct NewsWindow : Window {
 		switch (widget) {
 			case WID_N_CLOSEBOX:
 				NewsWindow::duration = 0;
-				delete this;
+				this->Close();
 				_forced_news = nullptr;
 				break;
 
@@ -1028,7 +1028,7 @@ static void ShowNewsMessage(const NewsItem *ni)
 bool HideActiveNewsMessage() {
 	NewsWindow *w = (NewsWindow*)FindWindowById(WC_NEWS_WINDOW, 0);
 	if (w == nullptr) return false;
-	delete w;
+	w->Close();
 	return true;
 }
 
diff --git a/src/osk_gui.cpp b/src/osk_gui.cpp
index 92b15eaba..6fb1ee5a0 100644
--- a/src/osk_gui.cpp
+++ b/src/osk_gui.cpp
@@ -170,7 +170,7 @@ struct OskWindow : public Window {
 						return;
 					}
 				}
-				delete this;
+				this->Close();
 				break;
 
 			case WID_OSK_CANCEL:
@@ -182,7 +182,7 @@ struct OskWindow : public Window {
 					qs->text.Assign(this->orig_str_buf);
 					qs->text.MovePos(WKC_END);
 					this->OnEditboxChanged(WID_OSK_TEXT);
-					delete this;
+					this->Close();
 				}
 				break;
 		}
@@ -205,7 +205,7 @@ struct OskWindow : public Window {
 	void OnFocusLost() override
 	{
 		VideoDriver::GetInstance()->EditBoxLostFocus();
-		delete this;
+		this->Close();
 	}
 };
 
diff --git a/src/rail_gui.cpp b/src/rail_gui.cpp
index 86f718984..bb5244ae7 100644
--- a/src/rail_gui.cpp
+++ b/src/rail_gui.cpp
@@ -434,10 +434,11 @@ struct BuildRailToolbarWindow : Window {
 		if (_settings_client.gui.link_terraform_toolbar) ShowTerraformToolbar(this);
 	}
 
-	~BuildRailToolbarWindow()
+	void Close() override
 	{
 		if (this->IsWidgetLowered(WID_RAT_BUILD_STATION)) SetViewportCatchmentStation(nullptr, true);
 		if (_settings_client.gui.link_terraform_toolbar) DeleteWindowById(WC_SCEN_LAND_GEN, 0, false);
+		this->Window::Close();
 	}
 
 	/**
@@ -1028,9 +1029,10 @@ public:
 		this->InvalidateData();
 	}
 
-	virtual ~BuildRailStationWindow()
+	void Close() override
 	{
 		DeleteWindowById(WC_SELECT_STATION, 0);
+		this->PickerWindowBase::Close();
 	}
 
 	/** Sort station classes by StationClassID. */
@@ -1695,9 +1697,10 @@ public:
 		this->OnInvalidateData();
 	}
 
-	~BuildSignalWindow()
+	void Close() override
 	{
 		_convert_signal_button = false;
+		this->PickerWindowBase::Close();
 	}
 
 	void OnInit() override
diff --git a/src/road_gui.cpp b/src/road_gui.cpp
index ae84404a2..c12e94c16 100644
--- a/src/road_gui.cpp
+++ b/src/road_gui.cpp
@@ -289,10 +289,11 @@ struct BuildRoadToolbarWindow : Window {
 		if (_settings_client.gui.link_terraform_toolbar) ShowTerraformToolbar(this);
 	}
 
-	~BuildRoadToolbarWindow()
+	void Close() override
 	{
 		if (_game_mode == GM_NORMAL && (this->IsWidgetLowered(WID_ROT_BUS_STATION) || this->IsWidgetLowered(WID_ROT_TRUCK_STATION))) SetViewportCatchmentStation(nullptr, true);
 		if (_settings_client.gui.link_terraform_toolbar) DeleteWindowById(WC_SCEN_LAND_GEN, 0, false);
+		this->Window::Close();
 	}
 
 	/**
@@ -1095,9 +1096,10 @@ struct BuildRoadStationWindow : public PickerWindowBase {
 		this->window_class = (rs == ROADSTOP_BUS) ? WC_BUS_STATION : WC_TRUCK_STATION;
 	}
 
-	virtual ~BuildRoadStationWindow()
+	void Close() override
 	{
 		DeleteWindowById(WC_SELECT_STATION, 0);
+		this->PickerWindowBase::Close();
 	}
 
 	void OnPaint() override
diff --git a/src/settings_gui.cpp b/src/settings_gui.cpp
index 559c39587..6fae298bc 100644
--- a/src/settings_gui.cpp
+++ b/src/settings_gui.cpp
@@ -172,11 +172,12 @@ struct GameOptionsWindow : Window {
 		this->OnInvalidateData(0);
 	}
 
-	~GameOptionsWindow()
+	void Close() override
 	{
 		DeleteWindowById(WC_CUSTOM_CURRENCY, 0);
 		DeleteWindowByClass(WC_TEXTFILE);
 		if (this->reload) _switch_mode = SM_MENU;
+		this->Window::Close();
 	}
 
 	/**
diff --git a/src/signs_gui.cpp b/src/signs_gui.cpp
index 93c4dd431..d7d93c905 100644
--- a/src/signs_gui.cpp
+++ b/src/signs_gui.cpp
@@ -527,7 +527,7 @@ struct SignWindow : Window, SignList {
 				FALLTHROUGH;
 
 			case WID_QES_CANCEL:
-				delete this;
+				this->Close();
 				break;
 		}
 	}
@@ -592,5 +592,5 @@ void DeleteRenameSignWindow(SignID sign)
 {
 	SignWindow *w = dynamic_cast<SignWindow *>(FindWindowById(WC_QUERY_STRING, WN_QUERY_STRING_SIGN));
 
-	if (w != nullptr && w->cur_sign == sign) delete w;
+	if (w != nullptr && w->cur_sign == sign) w->Close();
 }
diff --git a/src/smallmap_gui.cpp b/src/smallmap_gui.cpp
index bc0a7b447..7827620af 100644
--- a/src/smallmap_gui.cpp
+++ b/src/smallmap_gui.cpp
@@ -1095,7 +1095,12 @@ SmallMapWindow::SmallMapWindow(WindowDesc *desc, int window_number) : Window(des
 SmallMapWindow::~SmallMapWindow()
 {
 	delete this->overlay;
+}
+
+/* virtual */ void SmallMapWindow::Close()
+{
 	this->BreakIndustryChainLink();
+	this->Window::Close();
 }
 
 /**
diff --git a/src/smallmap_gui.h b/src/smallmap_gui.h
index e2fa9074d..a5552333c 100644
--- a/src/smallmap_gui.h
+++ b/src/smallmap_gui.h
@@ -178,6 +178,7 @@ public:
 	void SmallMapCenterOnCurrentPos();
 	Point GetStationMiddle(const Station *st) const;
 
+	void Close() override;
 	void SetStringParameters(int widget) const override;
 	void OnInit() override;
 	void OnPaint() override;
diff --git a/src/station_gui.cpp b/src/station_gui.cpp
index ab0eb5d1a..7fb1b66a4 100644
--- a/src/station_gui.cpp
+++ b/src/station_gui.cpp
@@ -1334,7 +1334,7 @@ struct StationViewWindow : public Window {
 		this->owner = Station::Get(window_number)->owner;
 	}
 
-	~StationViewWindow()
+	void Close() override
 	{
 		DeleteWindowById(WC_TRAINS_LIST,   VehicleListIdentifier(VL_STATION_LIST, VEH_TRAIN,    this->owner, this->window_number).Pack(), false);
 		DeleteWindowById(WC_ROADVEH_LIST,  VehicleListIdentifier(VL_STATION_LIST, VEH_ROAD,     this->owner, this->window_number).Pack(), false);
@@ -1342,6 +1342,7 @@ struct StationViewWindow : public Window {
 		DeleteWindowById(WC_AIRCRAFT_LIST, VehicleListIdentifier(VL_STATION_LIST, VEH_AIRCRAFT, this->owner, this->window_number).Pack(), false);
 
 		SetViewportCatchmentStation(Station::Get(this->window_number), false);
+		this->Window::Close();
 	}
 
 	/**
@@ -2285,11 +2286,12 @@ struct SelectStationWindow : Window {
 		_thd.freeze = true;
 	}
 
-	~SelectStationWindow()
+	void Close() override
 	{
 		if (_settings_client.gui.station_show_coverage) SetViewportCatchmentStation(nullptr, true);
 
 		_thd.freeze = false;
+		this->Window::Close();
 	}
 
 	void UpdateWidgetSize(int widget, Dimension *size, const Dimension &padding, Dimension *fill, Dimension *resize) override
@@ -2424,7 +2426,7 @@ static bool StationJoinerNeeded(const CommandContainer &cmd, TileArea ta)
 	Window *selection_window = FindWindowById(WC_SELECT_STATION, 0);
 	if (selection_window != nullptr) {
 		/* Abort current distant-join and start new one */
-		delete selection_window;
+		selection_window->Close();
 		UpdateTileSelection();
 	}
 
diff --git a/src/town_gui.cpp b/src/town_gui.cpp
index bd5893561..021590cb9 100644
--- a/src/town_gui.cpp
+++ b/src/town_gui.cpp
@@ -336,9 +336,10 @@ public:
 		this->SetWidgetDisabledState(WID_TV_CHANGE_NAME, _networking && !_network_server);
 	}
 
-	~TownViewWindow()
+	void Close() override
 	{
 		SetViewportCatchmentTown(Town::Get(this->window_number), false);
+		this->Window::Close();
 	}
 
 	void SetStringParameters(int widget) const override
diff --git a/src/vehicle_gui.cpp b/src/vehicle_gui.cpp
index 006664491..28155f724 100644
--- a/src/vehicle_gui.cpp
+++ b/src/vehicle_gui.cpp
@@ -1033,9 +1033,9 @@ struct RefitWindow : public Window {
 
 					if (this->order == INVALID_VEH_ORDER_ID) {
 						bool delete_window = this->selected_vehicle == v->index && this->num_vehicles == UINT8_MAX;
-						if (DoCommandP(v->tile, this->selected_vehicle, this->cargo->cargo | this->cargo->subtype << 8 | this->num_vehicles << 16, GetCmdRefitVeh(v)) && delete_window) delete this;
+						if (DoCommandP(v->tile, this->selected_vehicle, this->cargo->cargo | this->cargo->subtype << 8 | this->num_vehicles << 16, GetCmdRefitVeh(v)) && delete_window) this->Close();
 					} else {
-						if (DoCommandP(v->tile, v->index, this->cargo->cargo | this->order << 16, CMD_ORDER_REFIT)) delete this;
+						if (DoCommandP(v->tile, v->index, this->cargo->cargo | this->order << 16, CMD_ORDER_REFIT)) this->Close();
 					}
 				}
 				break;
@@ -2718,12 +2718,13 @@ public:
 		this->UpdateButtonStatus();
 	}
 
-	~VehicleViewWindow()
+	void Close() override
 	{
 		DeleteWindowById(WC_VEHICLE_ORDERS, this->window_number, false);
 		DeleteWindowById(WC_VEHICLE_REFIT, this->window_number, false);
 		DeleteWindowById(WC_VEHICLE_DETAILS, this->window_number, false);
 		DeleteWindowById(WC_VEHICLE_TIMETABLE, this->window_number, false);
+		this->Window::Close();
 	}
 
 	void UpdateWidgetSize(int widget, Dimension *size, const Dimension &padding, Dimension *fill, Dimension *resize) override
diff --git a/src/waypoint_gui.cpp b/src/waypoint_gui.cpp
index 40c3401b0..946d123c5 100644
--- a/src/waypoint_gui.cpp
+++ b/src/waypoint_gui.cpp
@@ -74,9 +74,10 @@ public:
 		this->OnInvalidateData(0);
 	}
 
-	~WaypointWindow()
+	void Close() override
 	{
 		DeleteWindowById(GetWindowClassForVehicleType(this->vt), VehicleListIdentifier(VL_STATION_LIST, this->vt, this->owner, this->window_number).Pack(), false);
+		this->Window::Close();
 	}
 
 	void SetStringParameters(int widget) const override
diff --git a/src/widgets/dropdown.cpp b/src/widgets/dropdown.cpp
index e838d7231..77b54d564 100644
--- a/src/widgets/dropdown.cpp
+++ b/src/widgets/dropdown.cpp
@@ -184,12 +184,11 @@ struct DropdownWindow : Window {
 		this->scrolling_timer  = GUITimer(MILLISECONDS_PER_TICK);
 	}
 
-	~DropdownWindow()
+	void Close() override
 	{
-		/* Make the dropdown "invisible", so it doesn't affect new window placement.
+		/* Finish closing the dropdown, so it doesn't affect new window placement.
 		 * Also mark it dirty in case the callback deals with the screen. (e.g. screenshots). */
-		*this->z_position = nullptr;
-		this->SetDirty();
+		this->Window::Close();
 
 		Window *w2 = FindWindowById(this->parent_wnd_class, this->parent_wnd_num);
 		if (w2 != nullptr) {
@@ -200,7 +199,7 @@ struct DropdownWindow : Window {
 		}
 	}
 
-	virtual Point OnInitialPosition(int16 sm_width, int16 sm_height, int window_number)
+	Point OnInitialPosition(int16 sm_width, int16 sm_height, int window_number) override
 	{
 		return this->position;
 	}
@@ -237,7 +236,7 @@ struct DropdownWindow : Window {
 		return false;
 	}
 
-	virtual void DrawWidget(const Rect &r, int widget) const
+	void DrawWidget(const Rect &r, int widget) const override
 	{
 		if (widget != WID_DM_ITEMS) return;
 
@@ -265,7 +264,7 @@ struct DropdownWindow : Window {
 		}
 	}
 
-	virtual void OnClick(Point pt, int widget, int click_count)
+	void OnClick(Point pt, int widget, int click_count) override
 	{
 		if (widget != WID_DM_ITEMS) return;
 		int item;
@@ -276,7 +275,7 @@ struct DropdownWindow : Window {
 		}
 	}
 
-	virtual void OnRealtimeTick(uint delta_ms)
+	void OnRealtimeTick(uint delta_ms) override
 	{
 		if (!this->scrolling_timer.Elapsed(delta_ms)) return;
 		this->scrolling_timer.SetInterval(MILLISECONDS_PER_TICK);
@@ -293,22 +292,19 @@ struct DropdownWindow : Window {
 		}
 	}
 
-	virtual void OnMouseLoop()
+	void OnMouseLoop() override
 	{
 		Window *w2 = FindWindowById(this->parent_wnd_class, this->parent_wnd_num);
 		if (w2 == nullptr) {
-			delete this;
+			this->Close();
 			return;
 		}
 
 		if (this->click_delay != 0 && --this->click_delay == 0) {
-			/* Make the dropdown "invisible", so it doesn't affect new window placement.
+			/* Close the dropdown, so it doesn't affect new window placement.
 			 * Also mark it dirty in case the callback deals with the screen. (e.g. screenshots). */
-			*this->z_position = nullptr;
-			this->SetDirty();
-
+			this->Close();
 			w2->OnDropdownSelect(this->parent_button, this->selected_index);
-			delete this;
 			return;
 		}
 
@@ -318,7 +314,7 @@ struct DropdownWindow : Window {
 			if (!_left_button_clicked) {
 				this->drag_mode = false;
 				if (!this->GetDropDownItem(item)) {
-					if (this->instant_close) delete this;
+					if (this->instant_close) this->Close();
 					return;
 				}
 				this->click_delay = 2;
@@ -509,7 +505,7 @@ int HideDropDownMenu(Window *pw)
 		if (pw->window_class == dw->parent_wnd_class &&
 				pw->window_number == dw->parent_wnd_num) {
 			int parent_button = dw->parent_button;
-			delete dw;
+			dw->Close();
 			return parent_button;
 		}
 	}
diff --git a/src/window.cpp b/src/window.cpp
index 036b17bcc..aae3efffb 100644
--- a/src/window.cpp
+++ b/src/window.cpp
@@ -56,6 +56,21 @@ static Window *_last_scroll_window = nullptr; ///< Window of the last scroll eve
 /** List of windows opened at the screen sorted from the front to back. */
 WindowList _z_windows;
 
+/** List of closed windows to delete. */
+/* static */ std::vector<Window *> Window::closed_windows;
+
+/**
+ * Delete all closed windows.
+ */
+/* static */ void Window::DeleteClosedWindows()
+{
+	for (Window *w : Window::closed_windows) delete w;
+	Window::closed_windows.clear();
+
+	/* Remove dead entries from the window list */
+	_z_windows.remove(nullptr);
+}
+
 /** If false, highlight is white, otherwise the by the widget defined colour. */
 bool _window_highlight_colour = false;
 
@@ -705,7 +720,7 @@ static void DispatchLeftClickEvent(Window *w, int x, int y, int click_count)
 		}
 
 		case WWT_CLOSEBOX: // 'X'
-			delete w;
+			w->Close();
 			return;
 
 		case WWT_CAPTION: // 'Title bar'
@@ -793,7 +808,7 @@ static void DispatchRightClickEvent(Window *w, int x, int y)
 
 	/* Right-click close is enabled and there is a closebox */
 	if (_settings_client.gui.right_mouse_wnd_close && w->nested_root->GetWidgetOfType(WWT_CLOSEBOX)) {
-		delete w;
+		w->Close();
 	} else if (_settings_client.gui.hover_delay_ms == 0 && !w->OnTooltip(pt, wid->index, TCC_RIGHT_CLICK) && wid->tool_tip != 0) {
 		GuiShowTooltips(w, wid->tool_tip, 0, nullptr, TCC_RIGHT_CLICK);
 	}
@@ -1068,16 +1083,21 @@ void Window::DeleteChildWindows(WindowClass wc) const
 {
 	Window *child = FindChildWindow(this, wc);
 	while (child != nullptr) {
-		delete child;
+		child->Close();
 		child = FindChildWindow(this, wc);
 	}
 }
 
 /**
- * Remove window and all its child windows from the window stack.
+ * Hide the window and all its child windows, and mark them for a later deletion.
  */
-Window::~Window()
+void Window::Close()
 {
+	/* Don't close twice. */
+	if (*this->z_position == nullptr) return;
+
+	*this->z_position = nullptr;
+
 	if (_thd.window_class == this->window_class &&
 			_thd.window_number == this->window_number) {
 		ResetObjectToPlace();
@@ -1094,21 +1114,29 @@ Window::~Window()
 
 	/* Make sure we don't try to access this window as the focused window when it doesn't exist anymore. */
 	if (_focused_window == this) {
-		/* Virtual functions get called statically in destructors, so make it explicit to remove any confusion. */
-		this->Window::OnFocusLost();
+		this->OnFocusLost();
 		_focused_window = nullptr;
 	}
 
 	this->DeleteChildWindows();
 
-	if (this->viewport != nullptr) DeleteWindowViewport(this);
-
 	this->SetDirty();
 
+	Window::closed_windows.push_back(this);
+}
+
+/**
+ * Remove window and all its child windows from the window stack.
+ */
+Window::~Window()
+{
+	/* Make sure the window is closed, deletion is allowed only in Window::DeleteClosedWindows(). */
+	assert(*this->z_position == nullptr);
+
+	if (this->viewport != nullptr) DeleteWindowViewport(this);
+
 	free(this->nested_array); // Contents is released through deletion of #nested_root.
 	delete this->nested_root;
-
-	*this->z_position = nullptr;
 }
 
 /**
@@ -1151,7 +1179,7 @@ void DeleteWindowById(WindowClass cls, WindowNumber number, bool force)
 {
 	Window *w = FindWindowById(cls, number);
 	if (w != nullptr && (force || (w->flags & WF_STICKY) == 0)) {
-		delete w;
+		w->Close();
 	}
 }
 
@@ -1164,7 +1192,7 @@ void DeleteWindowByClass(WindowClass cls)
 	/* Note: the container remains stable, even when deleting windows. */
 	for (Window *w : Window::Iterate()) {
 		if (w->window_class == cls) {
-			delete w;
+			w->Close();
 		}
 	}
 }
@@ -1180,7 +1208,7 @@ void DeleteCompanyWindows(CompanyID id)
 	/* Note: the container remains stable, even when deleting windows. */
 	for (Window *w : Window::Iterate()) {
 		if (w->owner == id) {
-			delete w;
+			w->Close();
 		}
 	}
 
@@ -1818,9 +1846,11 @@ void UnInitWindowSystem()
 {
 	UnshowCriticalError();
 
-	for (Window *w : Window::Iterate()) delete w;
+	for (Window *w : Window::Iterate()) w->Close();
 
-	_z_windows.clear();
+	Window::DeleteClosedWindows();
+
+	assert(_z_windows.empty());
 }
 
 /**
@@ -2968,7 +2998,7 @@ static void CheckSoftLimit()
 		if (deletable_count <= _settings_client.gui.window_soft_limit) break;
 
 		assert(last_deletable != nullptr);
-		delete last_deletable;
+		last_deletable->Close();
 	}
 }
 
@@ -2983,14 +3013,8 @@ void InputLoop()
 
 	CheckSoftLimit();
 
-	/* Remove dead entries from the window list */
-	for (auto it = _z_windows.begin(); it != _z_windows.end(); ) {
-		if (*it == nullptr) {
-			it = _z_windows.erase(it);
-		} else {
-			++it;
-		}
-	}
+	/* Process scheduled window deletion. */
+	Window::DeleteClosedWindows();
 
 	if (_input_events_this_tick != 0) {
 		/* The input loop is called only once per GameLoop() - so we can clear the counter here */
@@ -3237,7 +3261,7 @@ void CallWindowGameTickEvent()
 void DeleteNonVitalWindows()
 {
 	/* Note: the container remains stable, even when deleting windows. */
-	for (const Window *w : Window::Iterate()) {
+	for (Window *w : Window::Iterate()) {
 		if (w->window_class != WC_MAIN_WINDOW &&
 				w->window_class != WC_SELECT_GAME &&
 				w->window_class != WC_MAIN_TOOLBAR &&
@@ -3245,7 +3269,7 @@ void DeleteNonVitalWindows()
 				w->window_class != WC_TOOLTIPS &&
 				(w->flags & WF_STICKY) == 0) { // do not delete windows which are 'pinned'
 
-			delete w;
+			w->Close();
 		}
 	}
 }
@@ -3263,9 +3287,9 @@ void DeleteAllNonVitalWindows()
 	DeleteNonVitalWindows();
 
 	/* Note: the container remains stable, even when deleting windows. */
-	for (const Window *w : Window::Iterate()) {
+	for (Window *w : Window::Iterate()) {
 		if (w->flags & WF_STICKY) {
-			delete w;
+			w->Close();
 		}
 	}
 }
@@ -3288,9 +3312,9 @@ void DeleteAllMessages()
 void DeleteConstructionWindows()
 {
 	/* Note: the container remains stable, even when deleting windows. */
-	for (const Window *w : Window::Iterate()) {
+	for (Window *w : Window::Iterate()) {
 		if (w->window_desc->flags & WDF_CONSTRUCTION) {
-			delete w;
+			w->Close();
 		}
 	}
 
@@ -3483,12 +3507,11 @@ void RelocateAllWindows(int neww, int newh)
 }
 
 /**
- * Destructor of the base class PickerWindowBase
- * Main utility is to stop the base Window destructor from triggering
- * a free while the child will already be free, in this case by the ResetObjectToPlace().
+ * Hide the window and all its child windows, and mark them for a later deletion.
+ * Always call ResetObjectToPlace() when closing a PickerWindow.
  */
-PickerWindowBase::~PickerWindowBase()
+void PickerWindowBase::Close()
 {
-	*this->z_position = nullptr; // stop the ancestor from freeing the already (to be) child
 	ResetObjectToPlace();
+	this->Window::Close();
 }
diff --git a/src/window_gui.h b/src/window_gui.h
index 1195c6c49..c84ad333b 100644
--- a/src/window_gui.h
+++ b/src/window_gui.h
@@ -277,6 +277,9 @@ enum TooltipCloseCondition {
  * Data structure for an opened window
  */
 struct Window : ZeroedMemoryAllocator {
+private:
+	static std::vector<Window *> closed_windows;
+
 protected:
 	void InitializeData(WindowNumber window_number);
 	void InitializePositionSize(int x, int y, int min_width, int min_height);
@@ -284,11 +287,12 @@ protected:
 
 	std::vector<int> scheduled_invalidation_data;  ///< Data of scheduled OnInvalidateData() calls.
 
+	/* Protected to prevent deletion anywhere outside Window::DeleteClosedWindows(). */
+	virtual ~Window();
+
 public:
 	Window(WindowDesc *desc);
 
-	virtual ~Window();
-
 	/**
 	 * Helper allocation function to disallow something.
 	 * Don't allow arrays; arrays of Windows are pointless as you need
@@ -506,6 +510,8 @@ public:
 	static int SortButtonWidth();
 
 	void DeleteChildWindows(WindowClass wc = WC_INVALID) const;
+	virtual void Close();
+	static void DeleteClosedWindows();
 
 	void SetDirty() const;
 	void ReInit(int rx = 0, int ry = 0);
@@ -916,7 +922,7 @@ public:
 		this->parent = parent;
 	}
 
-	virtual ~PickerWindowBase();
+	void Close() override;
 };
 
 Window *BringWindowToFrontById(WindowClass cls, WindowNumber number);