diff --git a/src/ai/api/ai_log.cpp b/src/ai/api/ai_log.cpp
index 7a269030d3..af2295df1b 100644
--- a/src/ai/api/ai_log.cpp
+++ b/src/ai/api/ai_log.cpp
@@ -75,7 +75,7 @@
 
 	/* Also still print to debug window */
 	DEBUG(ai, level, "[%d] [%c] %s", (uint)_current_company, logc, log->lines[log->pos]);
-	InvalidateWindowData(WC_AI_DEBUG, 0, _current_company);
+	InvalidateWindowData(WC_AI_DEBUG, 0, _current_company, true); // breakpoint handling needs calling Invalidate immediately.
 }
 
 /* static */ void AILog::FreeLogPointer()
diff --git a/src/hotkeys.cpp b/src/hotkeys.cpp
index 686877bf38..5ad8f2bf95 100644
--- a/src/hotkeys.cpp
+++ b/src/hotkeys.cpp
@@ -74,7 +74,8 @@ static uint16 ParseCode(const char *start, const char *end)
 	}
 	if (end - start == 1) {
 		if (*start >= 'a' && *start <= 'z') return *start - ('a'-'A');
-		return *start;
+		/* Ignore invalid keycodes */
+		if (*(uint8*)start < 128) return *start;
 	}
 	return 0;
 }
@@ -99,10 +100,6 @@ static uint16 ParseKeycode(const char *start, const char *end)
 			if (code & ~WKC_SPECIAL_KEYS) return 0;
 			keycode |= code;
 		} else {
-			/* Ignore invalid keycodes */
-			if (code >= 128) {
-				return 0;
-			}
 			/* Ignore the code if it has more then 1 letter. */
 			if (keycode & ~WKC_SPECIAL_KEYS) return 0;
 			keycode |= code;
diff --git a/src/main_gui.cpp b/src/main_gui.cpp
index 3f43dcdc88..ed85860da5 100644
--- a/src/main_gui.cpp
+++ b/src/main_gui.cpp
@@ -435,7 +435,7 @@ struct MainWindow : Window
 	virtual void OnInvalidateData(int data)
 	{
 		/* Forward the message to the appropiate toolbar (ingame or scenario editor) */
-		InvalidateWindowData(WC_MAIN_TOOLBAR, 0, data);
+		InvalidateWindowData(WC_MAIN_TOOLBAR, 0, data, true);
 	}
 
 	static Hotkey<MainWindow> global_hotkeys[];
diff --git a/src/misc_gui.cpp b/src/misc_gui.cpp
index 33c22ed7a2..7d7aa37faa 100644
--- a/src/misc_gui.cpp
+++ b/src/misc_gui.cpp
@@ -198,6 +198,7 @@ public:
 		if (c != NULL) {
 			Money old_money = c->money;
 			c->money = INT64_MAX;
+			assert(_current_company == _local_company);
 			CommandCost costclear = DoCommand(tile, 0, 0, DC_NONE, CMD_LANDSCAPE_CLEAR);
 			c->money = old_money;
 			if (costclear.Succeeded()) {
@@ -329,6 +330,16 @@ public:
 	{
 		::ShowNewGRFInspectWindow(GetGrfSpecFeature(this->tile), this->tile);
 	}
+
+	virtual void OnInvalidateData(int data)
+	{
+		switch (data) {
+			case 1:
+				/* ReInit, "debug" sprite might have changed */
+				this->ReInit();
+				break;
+		}
+	}
 };
 
 /**
diff --git a/src/newgrf.cpp b/src/newgrf.cpp
index d987c3ed1b..e5211ccd37 100644
--- a/src/newgrf.cpp
+++ b/src/newgrf.cpp
@@ -6727,6 +6727,8 @@ static bool ChangeGRFParamValueNames(ByteReader *buf)
 		if (type != 'T' || id > _cur_parameter->max_value) {
 			grfmsg(2, "StaticGRFInfo: all child nodes of 'INFO'->'PARA'->param_num->'VALU' should have type 't' and the value/bit number as id");
 			if (!SkipUnknownInfo(buf, type)) return false;
+			type = buf->ReadByte();
+			continue;
 		}
 
 		byte langid = buf->ReadByte();
@@ -6770,7 +6772,9 @@ static bool HandleParameterInfo(ByteReader *buf)
 		uint32 id = buf->ReadDWord();
 		if (type != 'C' || id >= _cur_grfconfig->num_valid_params) {
 			grfmsg(2, "StaticGRFInfo: all child nodes of 'INFO'->'PARA' should have type 'C' and their parameter number as id");
-			return SkipUnknownInfo(buf, type);
+			if (!SkipUnknownInfo(buf, type)) return false;
+			type = buf->ReadByte();
+			continue;
 		}
 
 		if (id >= _cur_grfconfig->param_info.Length()) {
diff --git a/src/newgrf_debug_gui.cpp b/src/newgrf_debug_gui.cpp
index f4c3b985a6..b96ecbd7f8 100644
--- a/src/newgrf_debug_gui.cpp
+++ b/src/newgrf_debug_gui.cpp
@@ -518,9 +518,10 @@ void DeleteNewGRFInspectWindow(GrfSpecFeature feature, uint index)
 	WindowNumber wno = GetInspectWindowNumber(feature, index);
 	DeleteWindowById(WC_NEWGRF_INSPECT, wno);
 
-	/* Reinitialise the land information window to remove the "debug" sprite if needed. */
-	Window *w = FindWindowById(WC_LAND_INFO, 0);
-	if (w != NULL) w->ReInit();
+	/* Reinitialise the land information window to remove the "debug" sprite if needed.
+	 * Note: Since we might be called from a command here, it is important to not execute
+	 * the invalidation immediately. The landinfo window tests commands itself. */
+	InvalidateWindowData(WC_LAND_INFO, 0, 1);
 }
 
 /**
diff --git a/src/saveload/saveload.cpp b/src/saveload/saveload.cpp
index bff6b05d71..c4e314fedc 100644
--- a/src/saveload/saveload.cpp
+++ b/src/saveload/saveload.cpp
@@ -450,6 +450,11 @@ static void SlNullPointers()
 {
 	_sl.action = SLA_NULL;
 
+	/* We don't want any savegame conversion code to run
+	 * during NULLing; especially those that try to get
+	 * pointers from other pools. */
+	_sl_version = SAVEGAME_VERSION;
+
 	DEBUG(sl, 1, "Nulling pointers");
 
 	FOR_ALL_CHUNK_HANDLERS(ch) {
diff --git a/src/train_cmd.cpp b/src/train_cmd.cpp
index 754ae91986..e234c9d28c 100644
--- a/src/train_cmd.cpp
+++ b/src/train_cmd.cpp
@@ -264,7 +264,7 @@ void Train::ConsistChanged(bool same_length)
 	if (this->IsFrontEngine()) {
 		this->UpdateAcceleration();
 		SetWindowDirty(WC_VEHICLE_DETAILS, this->index);
-		InvalidateWindowData(WC_VEHICLE_REFIT, this->index);
+		InvalidateWindowData(WC_VEHICLE_REFIT, this->index); // Important, do not invalidate immediately. The refit window tests commands.
 	}
 }
 
@@ -1089,7 +1089,7 @@ static void NormaliseTrainHead(Train *head)
 	if (!head->IsFrontEngine()) return;
 
 	/* Update the refit button and window */
-	InvalidateWindowData(WC_VEHICLE_REFIT, head->index);
+	InvalidateWindowData(WC_VEHICLE_REFIT, head->index); // Important, do not invalidate immediately. The refit window tests commands.
 	SetWindowWidgetDirty(WC_VEHICLE_VIEW, head->index, VVW_WIDGET_REFIT_VEH);
 
 	/* If we don't have a unit number yet, set one. */
diff --git a/src/vehicle.cpp b/src/vehicle.cpp
index ec78d8f428..d2feacc075 100644
--- a/src/vehicle.cpp
+++ b/src/vehicle.cpp
@@ -2270,7 +2270,7 @@ void Vehicle::RemoveFromShared()
 	} else if (were_first) {
 		/* If we were the first one, update to the new first one.
 		 * Note: FirstShared() is already the new first */
-		InvalidateWindowData(GetWindowClassForVehicleType(this->type), vli.Pack(), this->FirstShared()->index | (1U << 31));
+		InvalidateWindowData(GetWindowClassForVehicleType(this->type), vli.Pack(), this->FirstShared()->index | (1U << 31), true);
 	}
 
 	this->next_shared     = NULL;
diff --git a/src/vehicle_gui.cpp b/src/vehicle_gui.cpp
index 96580dac9f..6efbecf533 100644
--- a/src/vehicle_gui.cpp
+++ b/src/vehicle_gui.cpp
@@ -585,6 +585,7 @@ struct RefitWindow : public Window {
 	 */
 	StringID GetCapacityString(RefitOption *option) const
 	{
+		assert(_current_company == _local_company);
 		Vehicle *v = Vehicle::Get(this->window_number);
 		CommandCost cost = DoCommand(v->tile, this->selected_vehicle, option->cargo | option->subtype << 8 |
 				this->num_vehicles << 16, DC_QUERY_COST, GetCmdRefitVeh(v->type));
@@ -1119,7 +1120,7 @@ static inline void ChangeVehicleWindow(WindowClass window_class, VehicleID from_
 			_thd.window_number = to_index;
 		}
 
-		/* Notify the window */
+		/* Notify the window immediately, without scheduling. */
 		w->InvalidateData();
 	}
 }
diff --git a/src/video/win32_v.cpp b/src/video/win32_v.cpp
index dc230456da..6aa9656be6 100644
--- a/src/video/win32_v.cpp
+++ b/src/video/win32_v.cpp
@@ -224,7 +224,7 @@ static void CALLBACK TrackMouseTimerProc(HWND hwnd, UINT msg, UINT event, DWORD
 	}
 }
 
-static bool MakeWindow(bool full_screen)
+bool VideoDriver_Win32::MakeWindow(bool full_screen)
 {
 	_fullscreen = full_screen;
 
@@ -259,11 +259,11 @@ static bool MakeWindow(bool full_screen)
 		if (ChangeDisplaySettings(&settings, CDS_FULLSCREEN | CDS_TEST) != DISP_CHANGE_SUCCESSFUL) {
 			RECT r;
 			GetWindowRect(GetDesktopWindow(), &r);
-			return _video_driver->ChangeResolution(r.right - r.left, r.bottom - r.top);
+			return this->ChangeResolution(r.right - r.left, r.bottom - r.top);
 		}
 
 		if (ChangeDisplaySettings(&settings, CDS_FULLSCREEN) != DISP_CHANGE_SUCCESSFUL) {
-			MakeWindow(false);  // don't care about the result
+			this->MakeWindow(false);  // don't care about the result
 			return false;  // the request failed
 		}
 	} else if (_wnd.fullscreen) {
@@ -646,7 +646,7 @@ static LRESULT CALLBACK WndProcGdi(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lP
 				if (active && minimized) {
 					/* Restore the game window */
 					ShowWindow(hwnd, SW_RESTORE);
-					MakeWindow(true);
+					static_cast<VideoDriver_Win32 *>(_video_driver)->MakeWindow(true);
 				} else if (!active && !minimized) {
 					/* Minimise the window and restore desktop */
 					ShowWindow(hwnd, SW_MINIMIZE);
@@ -800,7 +800,7 @@ const char *VideoDriver_Win32::Start(const char * const *parm)
 	_wnd.height_org = _cur_resolution.height;
 
 	AllocateDibSection(_cur_resolution.width, _cur_resolution.height);
-	MakeWindow(_fullscreen);
+	this->MakeWindow(_fullscreen);
 
 	MarkWholeScreenDirty();
 
@@ -915,10 +915,10 @@ bool VideoDriver_Win32::ChangeResolution(int w, int h)
 	_wnd.width = _wnd.width_org = w;
 	_wnd.height = _wnd.height_org = h;
 
-	return MakeWindow(_fullscreen); // _wnd.fullscreen screws up ingame resolution switching
+	return this->MakeWindow(_fullscreen); // _wnd.fullscreen screws up ingame resolution switching
 }
 
 bool VideoDriver_Win32::ToggleFullscreen(bool full_screen)
 {
-	return MakeWindow(full_screen);
+	return this->MakeWindow(full_screen);
 }
diff --git a/src/video/win32_v.h b/src/video/win32_v.h
index efd82671c8..4e267b2ab0 100644
--- a/src/video/win32_v.h
+++ b/src/video/win32_v.h
@@ -28,6 +28,8 @@ public:
 
 	/* virtual */ bool ToggleFullscreen(bool fullscreen);
 	/* virtual */ const char *GetName() const { return "win32"; }
+
+	bool MakeWindow(bool full_screen);
 };
 
 class FVideoDriver_Win32: public VideoDriverFactory<FVideoDriver_Win32> {
diff --git a/src/window.cpp b/src/window.cpp
index 2c6f1f1e16..57c753c52c 100644
--- a/src/window.cpp
+++ b/src/window.cpp
@@ -2420,6 +2420,7 @@ void UpdateWindows()
 
 			if (!(w->flags4 & WF_WHITE_BORDER_MASK)) w->SetDirty();
 		}
+		w->ProcessScheduledInvalidations();
 	}
 
 	DrawDirtyBlocks();
@@ -2476,29 +2477,47 @@ void SetWindowClassesDirty(WindowClass cls)
 
 /**
  * Mark window data of the window of a given class and specific window number as invalid (in need of re-computing)
+ * Note that by default the invalidation is not executed immediately but is scheduled till the next redraw.
+ * The asynchronous execution is important to prevent GUI code being executed from command scope.
  * @param cls Window class
  * @param number Window number within the class
  * @param data The data to invalidate with
+ * @param immediately If true then do not schedule the event, but execute immediately.
  */
-void InvalidateWindowData(WindowClass cls, WindowNumber number, int data)
+void InvalidateWindowData(WindowClass cls, WindowNumber number, int data, bool immediately)
 {
 	Window *w;
 	FOR_ALL_WINDOWS_FROM_BACK(w) {
-		if (w->window_class == cls && w->window_number == number) w->InvalidateData(data);
+		if (w->window_class == cls && w->window_number == number) {
+			if (immediately) {
+				w->InvalidateData(data);
+			} else {
+				w->ScheduleInvalidateData(data);
+			}
+		}
 	}
 }
 
 /**
  * Mark window data of all windows of a given class as invalid (in need of re-computing)
+ * Note that by default the invalidation is not executed immediately but is scheduled till the next redraw.
+ * The asynchronous execution is important to prevent GUI code being executed from command scope.
  * @param cls Window class
  * @param data The data to invalidate with
+ * @param immediately If true then do not schedule the event, but execute immediately.
  */
-void InvalidateWindowClassesData(WindowClass cls, int data)
+void InvalidateWindowClassesData(WindowClass cls, int data, bool immediately)
 {
 	Window *w;
 
 	FOR_ALL_WINDOWS_FROM_BACK(w) {
-		if (w->window_class == cls) w->InvalidateData(data);
+		if (w->window_class == cls) {
+			if (immediately) {
+				w->InvalidateData(data);
+			} else {
+				w->ScheduleInvalidateData(data);
+			}
+		}
 	}
 }
 
diff --git a/src/window_func.h b/src/window_func.h
index 3d51644f6d..43f50111d4 100644
--- a/src/window_func.h
+++ b/src/window_func.h
@@ -34,8 +34,8 @@ void ResetWindowSystem();
 void SetupColoursAndInitialWindow();
 void InputLoop();
 
-void InvalidateWindowData(WindowClass cls, WindowNumber number, int data = 0);
-void InvalidateWindowClassesData(WindowClass cls, int data = 0);
+void InvalidateWindowData(WindowClass cls, WindowNumber number, int data = 0, bool immediately = false);
+void InvalidateWindowClassesData(WindowClass cls, int data = 0, bool immediately = false);
 
 void DeleteNonVitalWindows();
 void DeleteAllNonVitalWindows();
diff --git a/src/window_gui.h b/src/window_gui.h
index 724d77880d..3254ee8c4c 100644
--- a/src/window_gui.h
+++ b/src/window_gui.h
@@ -17,6 +17,7 @@
 #include "company_type.h"
 #include "tile_type.h"
 #include "widget_type.h"
+#include "core/smallvec_type.hpp"
 
 /** State of handling an event. */
 enum EventState {
@@ -221,6 +222,8 @@ protected:
 	void InitializePositionSize(int x, int y, int min_width, int min_height);
 	void FindWindowPlacementAndResize(int def_width, int def_height);
 
+	SmallVector<int, 4> scheduled_invalidation_data;  ///< Data of scheduled OnInvalidateData() calls.
+
 public:
 	Window();
 
@@ -438,6 +441,28 @@ public:
 		this->OnInvalidateData(data);
 	}
 
+	/**
+	 * Schedule a invalidation call for next redraw.
+	 * Important for asynchronous invalidation from commands.
+	 * @param data The data to invalidate with
+	 */
+	void ScheduleInvalidateData(int data = 0)
+	{
+		this->SetDirty();
+		*this->scheduled_invalidation_data.Append() = data;
+	}
+
+	/**
+	 * Process all scheduled invalidations.
+	 */
+	void ProcessScheduledInvalidations()
+	{
+		for (int *data = this->scheduled_invalidation_data.Begin(); this->window_class != WC_INVALID && data != this->scheduled_invalidation_data.End(); data++) {
+			this->OnInvalidateData(*data);
+		}
+		this->scheduled_invalidation_data.Clear();
+	}
+
 	/*** Event handling ***/
 
 	/**