(svn r26652) [1.4] -Backport from trunk:

- Fix: Segmentation fault when encountering a .obg/.obs/.obm with empty string/zero length MD5 checksums [FS#6038] (r26637)
- Fix: The 'Load' button was not properly enabled/disabled for old savegames without NewGRF information (r26634)
- Fix: If the video driver fails to supply a list of resolutions, display an error message [FS#6012] (r26629)

src/base_media_func.h

@@ -100,7 +100,7 @@ bool BaseSet<T, Tnum_files, Tsearch_in_tars>::FillSetDetails(IniFile *ini, const
 
 		/* Then find the MD5 checksum */
 		item = md5s->GetItem(filename, false);
-		if (item == NULL) {
+		if (item == NULL || item->value == NULL) {
 			DEBUG(grf, 0, "No MD5 checksum specified for: %s (in %s)", filename, full_filename);
 			return false;
 		}

src/fios_gui.cpp

@@ -533,7 +533,7 @@ public:
 					if (_saveload_mode == SLD_LOAD_HEIGHTMAP) {
 						delete this;
 						ShowHeightmapLoad();
-					} else if (_load_check_data.grf_compatibility != GLC_NOT_FOUND || _settings_client.gui.UserIsAllowedToChangeNewGRFs()) {
+					} 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;
@@ -550,7 +550,7 @@ public:
 			case WID_SL_MISSING_NEWGRFS:
 				if (!_network_available) {
 					ShowErrorMessage(STR_NETWORK_ERROR_NOTAVAILABLE, INVALID_STRING_ID, WL_ERROR);
-				} else {
+				} else if (_load_check_data.HasNewGrfs()) {
 #if defined(ENABLE_NETWORK)
 					ShowMissingContentWindow(_load_check_data.grfconfig);
 #endif
@@ -691,7 +691,7 @@ public:
 				}
 				if (_saveload_mode == SLD_LOAD_GAME || _saveload_mode == SLD_LOAD_SCENARIO) {
 					this->SetWidgetDisabledState(WID_SL_LOAD_BUTTON,
-							this->selected == NULL || _load_check_data.HasErrors() || !(_load_check_data.grf_compatibility != GLC_NOT_FOUND || _settings_client.gui.UserIsAllowedToChangeNewGRFs()));
+							this->selected == NULL || _load_check_data.HasErrors() || !(!_load_check_data.HasNewGrfs() || _load_check_data.grf_compatibility != GLC_NOT_FOUND || _settings_client.gui.UserIsAllowedToChangeNewGRFs()));
 					this->SetWidgetDisabledState(WID_SL_NEWGRF_INFO,
 							!_load_check_data.HasNewGrfs());
 					this->SetWidgetDisabledState(WID_SL_MISSING_NEWGRFS,

src/lang/english.txt

@@ -969,6 +969,7 @@ STR_GAME_OPTIONS_BASE_MUSIC_TOOLTIP                             :{BLACK}Select t
 STR_GAME_OPTIONS_BASE_MUSIC_STATUS                              :{RED}{NUM} corrupted file{P "" s}
 STR_GAME_OPTIONS_BASE_MUSIC_DESCRIPTION_TOOLTIP                 :{BLACK}Additional information about the base music set
 
+STR_ERROR_RESOLUTION_LIST_FAILED                                :{WHITE}Failed to retrieve a list of supported resolutions
 STR_ERROR_FULLSCREEN_FAILED                                     :{WHITE}Fullscreen mode failed
 
 # Custom currency window

src/settings_gui.cpp

@@ -265,6 +265,8 @@ struct GameOptionsWindow : Window {
 			}
 
 			case WID_GO_RESOLUTION_DROPDOWN: // Setup resolution dropdown
+				if (_num_resolutions == 0) break;
+
 				list = new DropDownList();
 				*selected_index = GetCurRes();
 				for (int i = 0; i < _num_resolutions; i++) {
@@ -440,6 +442,8 @@ struct GameOptionsWindow : Window {
 				DropDownList *list = this->BuildDropDownList(widget, &selected);
 				if (list != NULL) {
 					ShowDropDownList(this, list, selected, widget);
+				} else {
+					if (widget == WID_GO_RESOLUTION_DROPDOWN) ShowErrorMessage(STR_ERROR_RESOLUTION_LIST_FAILED, INVALID_STRING_ID, WL_ERROR);
 				}
 				break;
 			}

src/widgets/dropdown.cpp

@@ -114,6 +114,8 @@ struct DropdownWindow : Window {
 	DropdownWindow(Window *parent, const DropDownList *list, int selected, int button, bool instant_close, const Point &position, const Dimension &size, Colours wi_colour, bool scroll)
 			: Window(&_dropdown_desc)
 	{
+		assert(list->Length() > 0);
+
 		this->position = position;
 
 		this->CreateNestedTree();