Index: src/gfxinit.cpp
===================================================================
--- src/gfxinit.cpp	(revision 27730)
+++ src/gfxinit.cpp	(working copy)
@@ -230,6 +230,14 @@
 
 	LoadNewGRF(SPR_NEWGRFS_BASE, i, 2);
 
+	uint total_extra_graphics = SPR_NEWGRFS_BASE - SPR_OPENTTD_BASE;
+	_missing_extra_graphics = GetSpriteCountForSlot(i, SPR_OPENTTD_BASE, SPR_NEWGRFS_BASE);
+	DEBUG(sprite, 1, "%u extra sprites, %u from baseset, %u from fallback", total_extra_graphics, total_extra_graphics - _missing_extra_graphics, _missing_extra_graphics);
+
+	/* The original baseset extra graphics intentionally make use of the fallback graphics.
+	 * Let's say everything which provides less than 500 sprites misses the rest intentionally. */
+	if (500 + _missing_extra_graphics > total_extra_graphics) _missing_extra_graphics = 0;
+
 	/* Free and remove the top element. */
 	delete extra;
 	delete master;
Index: src/intro_gui.cpp
===================================================================
--- src/intro_gui.cpp	(revision 27730)
+++ src/intro_gui.cpp	(working copy)
@@ -60,13 +60,21 @@
 
 	virtual void OnInit()
 	{
-		bool missing = _current_language->missing >= _settings_client.gui.missing_strings_threshold && !IsReleasedVersion();
-		this->GetWidget<NWidgetStacked>(WID_SGI_TRANSLATION_SELECTION)->SetDisplayedPlane(missing ? 0 : SZSP_NONE);
+		bool missing_sprites = _missing_extra_graphics > 0 && !IsReleasedVersion();
+		this->GetWidget<NWidgetStacked>(WID_SGI_BASESET_SELECTION)->SetDisplayedPlane(missing_sprites ? 0 : SZSP_NONE);
+
+		bool missing_lang = _current_language->missing >= _settings_client.gui.missing_strings_threshold && !IsReleasedVersion();
+		this->GetWidget<NWidgetStacked>(WID_SGI_TRANSLATION_SELECTION)->SetDisplayedPlane(missing_lang ? 0 : SZSP_NONE);
 	}
 
 	virtual void DrawWidget(const Rect &r, int widget) const
 	{
 		switch (widget) {
+			case WID_SGI_BASESET:
+				SetDParam(0, _missing_extra_graphics);
+				DrawStringMultiLine(r.left, r.right, r.top,  r.bottom, STR_INTRO_BASESET, TC_FROMSTRING, SA_CENTER);
+				break;
+
 			case WID_SGI_TRANSLATION:
 				SetDParam(0, _current_language->missing);
 				DrawStringMultiLine(r.left, r.right, r.top,  r.bottom, STR_INTRO_TRANSLATION, TC_FROMSTRING, SA_CENTER);
@@ -76,20 +84,29 @@
 
 	virtual void UpdateWidgetSize(int widget, Dimension *size, const Dimension &padding, Dimension *fill, Dimension *resize)
 	{
+		StringID str = 0;
 		switch (widget) {
-			case WID_SGI_TRANSLATION: {
+			case WID_SGI_BASESET:
+				SetDParam(0, _missing_extra_graphics);
+				str = STR_INTRO_BASESET;
+				break;
+
+			case WID_SGI_TRANSLATION:
 				SetDParam(0, _current_language->missing);
-				int height = GetStringHeight(STR_INTRO_TRANSLATION, size->width);
-				if (height > 3 * FONT_HEIGHT_NORMAL) {
-					/* Don't let the window become too high. */
-					Dimension textdim = GetStringBoundingBox(STR_INTRO_TRANSLATION);
-					textdim.height *= 3;
-					textdim.width -= textdim.width / 2;
-					*size = maxdim(*size, textdim);
-				} else {
-					size->height = height + padding.height;
-				}
+				str = STR_INTRO_TRANSLATION;
 				break;
+		}
+
+		if (str != 0) {
+			int height = GetStringHeight(str, size->width);
+			if (height > 3 * FONT_HEIGHT_NORMAL) {
+				/* Don't let the window become too high. */
+				Dimension textdim = GetStringBoundingBox(str);
+				textdim.height *= 3;
+				textdim.width -= textdim.width / 2;
+				*size = maxdim(*size, textdim);
+			} else {
+				size->height = height + padding.height;
 			}
 		}
 	}
@@ -199,6 +216,11 @@
 	EndContainer(),
 
 	NWidget(NWID_SPACER), SetMinimalSize(0, 7),
+	NWidget(NWID_SELECTION, INVALID_COLOUR, WID_SGI_BASESET_SELECTION),
+		NWidget(NWID_VERTICAL),
+			NWidget(WWT_EMPTY, COLOUR_ORANGE, WID_SGI_BASESET), SetMinimalSize(316, 12), SetFill(1, 0), SetPadding(0, 10, 7, 10),
+		EndContainer(),
+	EndContainer(),
 	NWidget(NWID_SELECTION, INVALID_COLOUR, WID_SGI_TRANSLATION_SELECTION),
 		NWidget(NWID_VERTICAL),
 			NWidget(WWT_EMPTY, COLOUR_ORANGE, WID_SGI_TRANSLATION), SetMinimalSize(316, 12), SetFill(1, 0), SetPadding(0, 10, 7, 10),
Index: src/lang/english.txt
===================================================================
--- src/lang/english.txt	(revision 27730)
+++ src/lang/english.txt	(working copy)
@@ -1761,6 +1761,7 @@
 STR_INTRO_TOOLTIP_SCRIPT_SETTINGS                               :{BLACK}Display AI/Game script settings
 STR_INTRO_TOOLTIP_QUIT                                          :{BLACK}Exit 'OpenTTD'
 
+STR_INTRO_BASESET                                               :{BLACK}The currently selected base graphics set is missing {NUM} sprite{P "" s}. Please check for updates for the baseset.
 STR_INTRO_TRANSLATION                                           :{BLACK}This translation misses {NUM} string{P "" s}. Please help make OpenTTD better by signing up as translator. See readme.txt for details.
 
 # Quit window
@@ -2907,8 +2908,6 @@
 STR_NEWGRF_ERROR_CORRUPT_SPRITE                                 :{YELLOW}{RAW_STRING} contains a corrupt sprite. All corrupt sprites will be shown as a red question mark (?)
 STR_NEWGRF_ERROR_MULTIPLE_ACTION_8                              :Contains multiple Action 8 entries (sprite {3:NUM})
 STR_NEWGRF_ERROR_READ_BOUNDS                                    :Read past end of pseudo-sprite (sprite {3:NUM})
-STR_NEWGRF_ERROR_MISSING_SPRITES                                :{WHITE}The currently used base graphics set is missing a number of sprites.{}Please update the base graphics set
-STR_NEWGRF_ERROR_MISSING_SPRITES_UNSTABLE                       :{WHITE}The currently used base graphics set is missing a number of sprites.{}Please update the base graphics set.{}Since you are playing a {YELLOW}development snapshot of OpenTTD{WHITE}, you might also need a {YELLOW}development snapshot of the base graphics{WHITE}
 STR_NEWGRF_ERROR_GRM_FAILED                                     :Requested GRF resources not available (sprite {3:NUM})
 STR_NEWGRF_ERROR_FORCEFULLY_DISABLED                            :{1:RAW_STRING} was disabled by {2:RAW_STRING}
 STR_NEWGRF_ERROR_INVALID_SPRITE_LAYOUT                          :Invalid/unknown sprite layout format (sprite {3:NUM})
Index: src/newgrf.cpp
===================================================================
--- src/newgrf.cpp	(revision 27730)
+++ src/newgrf.cpp	(working copy)
@@ -5694,35 +5694,6 @@
 }
 
 /**
- * Check whether we are (obviously) missing some of the extra
- * (Action 0x05) sprites that we like to use.
- * When missing sprites are found a warning will be shown.
- */
-void CheckForMissingSprites()
-{
-	/* Don't break out quickly, but allow to check the other
-	 * sprites as well, so we can give the best information. */
-	bool missing = false;
-	for (uint8 i = 0; i < lengthof(_action5_types); i++) {
-		const Action5Type *type = &_action5_types[i];
-		if (type->block_type == A5BLOCK_INVALID) continue;
-
-		for (uint j = 0; j < type->max_sprites; j++) {
-			if (!SpriteExists(type->sprite_base + j)) {
-				DEBUG(grf, 0, "%s sprites are missing", type->name);
-				missing = true;
-				/* No need to log more of the same. */
-				break;
-			}
-		}
-	}
-
-	if (missing) {
-		ShowErrorMessage(IsReleasedVersion() ? STR_NEWGRF_ERROR_MISSING_SPRITES : STR_NEWGRF_ERROR_MISSING_SPRITES_UNSTABLE, INVALID_STRING_ID, WL_CRITICAL);
-	}
-}
-
-/**
  * Reads a variable common to VarAction2 and Action7/9/D.
  *
  * Returns VarAction2 variable 'param' resp. Action7/9/D variable '0x80 + param'.
Index: src/newgrf_config.cpp
===================================================================
--- src/newgrf_config.cpp	(revision 27730)
+++ src/newgrf_config.cpp	(working copy)
@@ -192,6 +192,7 @@
 GRFConfig *_grfconfig;
 GRFConfig *_grfconfig_newgame;
 GRFConfig *_grfconfig_static;
+uint _missing_extra_graphics = 0;
 
 /**
  * Construct a new GRFError.
Index: src/newgrf_config.h
===================================================================
--- src/newgrf_config.h	(revision 27730)
+++ src/newgrf_config.h	(working copy)
@@ -202,6 +202,7 @@
 extern GRFConfig *_grfconfig;         ///< First item in list of current GRF set up
 extern GRFConfig *_grfconfig_newgame; ///< First item in list of default GRF set up
 extern GRFConfig *_grfconfig_static;  ///< First item in list of static GRF set up
+extern uint _missing_extra_graphics;  ///< Number of sprites provided by the fallback extra GRF, i.e. missing in the baseset.
 
 /** Callback for NewGRF scanning. */
 struct NewGRFScanCallback {
@@ -214,7 +215,6 @@
 size_t GRFGetSizeOfDataSection(FILE *f);
 
 void ScanNewGRFFiles(NewGRFScanCallback *callback);
-void CheckForMissingSprites();
 const GRFConfig *FindGRFConfig(uint32 grfid, FindGRFConfigMode mode, const uint8 *md5sum = NULL, uint32 desired_version = 0);
 GRFConfig *GetGRFConfig(uint32 grfid, uint32 mask = 0xFFFFFFFF);
 GRFConfig **CopyGRFConfigList(GRFConfig **dst, const GRFConfig *src, bool init_only);
Index: src/openttd.cpp
===================================================================
--- src/openttd.cpp	(revision 27730)
+++ src/openttd.cpp	(working copy)
@@ -339,7 +339,6 @@
 	_pause_mode = PM_UNPAUSED;
 	_cursor.fix_at = false;
 
-	if (load_newgrfs) CheckForMissingSprites();
 	CheckForMissingGlyphs();
 
 	/* Play main theme */
Index: src/script/api/game/game_window.hpp.sq
===================================================================
--- src/script/api/game/game_window.hpp.sq	(revision 27730)
+++ src/script/api/game/game_window.hpp.sq	(working copy)
@@ -582,6 +582,8 @@
 	SQGSWindow.DefSQConst(engine, ScriptWindow::WID_SGI_ARCTIC_LANDSCAPE,                  "WID_SGI_ARCTIC_LANDSCAPE");
 	SQGSWindow.DefSQConst(engine, ScriptWindow::WID_SGI_TROPIC_LANDSCAPE,                  "WID_SGI_TROPIC_LANDSCAPE");
 	SQGSWindow.DefSQConst(engine, ScriptWindow::WID_SGI_TOYLAND_LANDSCAPE,                 "WID_SGI_TOYLAND_LANDSCAPE");
+	SQGSWindow.DefSQConst(engine, ScriptWindow::WID_SGI_BASESET_SELECTION,                 "WID_SGI_BASESET_SELECTION");
+	SQGSWindow.DefSQConst(engine, ScriptWindow::WID_SGI_BASESET,                           "WID_SGI_BASESET");
 	SQGSWindow.DefSQConst(engine, ScriptWindow::WID_SGI_TRANSLATION_SELECTION,             "WID_SGI_TRANSLATION_SELECTION");
 	SQGSWindow.DefSQConst(engine, ScriptWindow::WID_SGI_TRANSLATION,                       "WID_SGI_TRANSLATION");
 	SQGSWindow.DefSQConst(engine, ScriptWindow::WID_SGI_OPTIONS,                           "WID_SGI_OPTIONS");
Index: src/script/api/script_window.hpp
===================================================================
--- src/script/api/script_window.hpp	(revision 27730)
+++ src/script/api/script_window.hpp	(working copy)
@@ -1497,8 +1497,10 @@
 		WID_SGI_ARCTIC_LANDSCAPE                     = ::WID_SGI_ARCTIC_LANDSCAPE,                     ///< Select arctic landscape button.
 		WID_SGI_TROPIC_LANDSCAPE                     = ::WID_SGI_TROPIC_LANDSCAPE,                     ///< Select tropic landscape button.
 		WID_SGI_TOYLAND_LANDSCAPE                    = ::WID_SGI_TOYLAND_LANDSCAPE,                    ///< Select toyland landscape button.
+		WID_SGI_BASESET_SELECTION                    = ::WID_SGI_BASESET_SELECTION,                    ///< Baseset selection.
+		WID_SGI_BASESET                              = ::WID_SGI_BASESET,                              ///< Baseset errors.
 		WID_SGI_TRANSLATION_SELECTION                = ::WID_SGI_TRANSLATION_SELECTION,                ///< Translation selection.
-		WID_SGI_TRANSLATION                          = ::WID_SGI_TRANSLATION,                          ///< Translation.
+		WID_SGI_TRANSLATION                          = ::WID_SGI_TRANSLATION,                          ///< Translation errors.
 		WID_SGI_OPTIONS                              = ::WID_SGI_OPTIONS,                              ///< Options button.
 		WID_SGI_HIGHSCORE                            = ::WID_SGI_HIGHSCORE,                            ///< Highscore button.
 		WID_SGI_SETTINGS_OPTIONS                     = ::WID_SGI_SETTINGS_OPTIONS,                     ///< Settings button.
Index: src/spritecache.cpp
===================================================================
--- src/spritecache.cpp	(revision 27730)
+++ src/spritecache.cpp	(working copy)
@@ -150,6 +150,25 @@
 }
 
 /**
+ * Count the sprites which originate from a specific file slot in a range of SpriteIDs.
+ * @param file_slot FIOS file slot.
+ * @param begin First sprite in range.
+ * @param end First sprite not in range.
+ * @return Number of sprites.
+ */
+uint GetSpriteCountForSlot(uint file_slot, SpriteID begin, SpriteID end)
+{
+	uint count = 0;
+	for (SpriteID i = begin; i != end; i++) {
+		if (SpriteExists(i)) {
+			SpriteCache *sc = GetSpriteCache(i);
+			if (sc->file_slot == file_slot) count++;
+		}
+	}
+	return count;
+}
+
+/**
  * Get a reasonable (upper bound) estimate of the maximum
  * SpriteID used in OpenTTD; there will be no sprites with
  * a higher SpriteID, although there might be up to roughly
Index: src/spritecache.h
===================================================================
--- src/spritecache.h	(revision 27730)
+++ src/spritecache.h	(working copy)
@@ -32,6 +32,7 @@
 
 SpriteType GetSpriteType(SpriteID sprite);
 uint GetOriginFileSlot(SpriteID sprite);
+uint GetSpriteCountForSlot(uint file_slot, SpriteID begin, SpriteID end);
 uint GetMaxSpriteID();
 
 
Index: src/widgets/intro_widget.h
===================================================================
--- src/widgets/intro_widget.h	(revision 27730)
+++ src/widgets/intro_widget.h	(working copy)
@@ -24,8 +24,10 @@
 	WID_SGI_ARCTIC_LANDSCAPE,      ///< Select arctic landscape button.
 	WID_SGI_TROPIC_LANDSCAPE,      ///< Select tropic landscape button.
 	WID_SGI_TOYLAND_LANDSCAPE,     ///< Select toyland landscape button.
+	WID_SGI_BASESET_SELECTION,     ///< Baseset selection.
+	WID_SGI_BASESET,               ///< Baseset errors.
 	WID_SGI_TRANSLATION_SELECTION, ///< Translation selection.
-	WID_SGI_TRANSLATION,           ///< Translation.
+	WID_SGI_TRANSLATION,           ///< Translation errors.
 	WID_SGI_OPTIONS,               ///< Options button.
 	WID_SGI_HIGHSCORE,             ///< Highscore button.
 	WID_SGI_SETTINGS_OPTIONS,      ///< Settings button.