diff --git a/desktop/gui.cpp b/desktop/gui.cpp
index 5a200d4..bcde788 100644
--- a/desktop/gui.cpp
+++ b/desktop/gui.cpp
@@ -3513,7 +3513,7 @@ int ProcessSpacerMessage(EsElement *element, EsMessage *message) {
 	return 0;
 }
 
-EsElement *EsSpacerCreate(EsElement *panel, uint64_t flags, const EsStyle *style, int width, int height) {
+EsSpacer *EsSpacerCreate(EsElement *panel, uint64_t flags, const EsStyle *style, int width, int height) {
 	EsSpacer *spacer = (EsSpacer *) EsHeapAllocate(sizeof(EsSpacer), true);
 	if (!spacer) return nullptr;
 	spacer->Initialise(panel, flags, ProcessSpacerMessage, style);
@@ -3523,6 +3523,12 @@ EsElement *EsSpacerCreate(EsElement *panel, uint64_t flags, const EsStyle *style
 	return spacer;
 }
 
+void EsSpacerChangeStyle(EsSpacer *spacer, const EsStyle *style) {
+	EsMessageMutexCheck();
+	EsAssert(spacer->messageClass == ProcessSpacerMessage);
+	spacer->SetStyle(style);
+}
+
 EsElement *EsCustomElementCreate(EsElement *parent, uint64_t flags, const EsStyle *style) {
 	EsElement *element = (EsElement *) EsHeapAllocate(sizeof(EsElement), true);
 	if (!element) return nullptr;
diff --git a/desktop/os.header b/desktop/os.header
index cffa83a..f487df1 100644
--- a/desktop/os.header
+++ b/desktop/os.header
@@ -18,6 +18,7 @@ opaque_type EsListDisplay      EsElement;
 opaque_type EsCanvasPane       EsElement;
 opaque_type EsSlider           EsElement;
 opaque_type EsScrollView       EsElement;
+opaque_type EsSpacer           EsElement;
 opaque_type EsTextPlan         none;
 opaque_type EsPaintTarget      none;
 opaque_type EsUndoManager      none;
@@ -2533,7 +2534,7 @@ function void EsSliderSetValue(EsSlider *slider, double newValue, bool sendUpdat
 // Panels, spacers and splitters.
 
 function EsPanel *EsPanelCreate(EsElement *parent, uint64_t flags = ES_FLAGS_DEFAULT, const EsStyle *style = ES_NULL);
-function EsElement *EsSpacerCreate(EsElement *parent, uint64_t flags = ES_FLAGS_DEFAULT, const EsStyle *style = ES_NULL, int width = 0, int height = 0);
+function EsSpacer *EsSpacerCreate(EsElement *parent, uint64_t flags = ES_FLAGS_DEFAULT, const EsStyle *style = ES_NULL, int width = 0, int height = 0);
 function EsSplitter *EsSplitterCreate(EsElement *parent, uint64_t flags = ES_FLAGS_DEFAULT, const EsStyle *style = ES_NULL);
 function EsCanvasPane *EsCanvasPaneCreate(EsElement *parent, uint64_t flags = ES_FLAGS_DEFAULT, const EsStyle *style = ES_NULL);
 
@@ -2546,6 +2547,8 @@ function void EsPanelStartMovementAnimation(EsPanel *panel, float timeMultiplier
 
 function EsButton *EsPanelRadioGroupGetChecked(EsPanel *panel);
 
+function void EsSpacerChangeStyle(EsSpacer *spacer, const EsStyle *newStyle);
+
 // Static displays.
 
 function EsIconDisplay *EsIconDisplayCreate(EsElement *parent, uint64_t flags = ES_FLAGS_DEFAULT, const EsStyle *style = ES_NULL, uint32_t iconID = 0);
diff --git a/util/api_table.ini b/util/api_table.ini
index ec83299..a0e1de4 100644
--- a/util/api_table.ini
+++ b/util/api_table.ini
@@ -345,6 +345,7 @@ EsListDisplayCreate=343
 EsCRTfabsf=344
 EsCRTisnanf=345
 EsListDisplaySetCounterContinuation=346
+EsSpacerChangeStyle=347
 EsImageDisplayLoadBits=348
 EsImageDisplayLoadFromMemory=349
 EsTextDisplaySetupSyntaxHighlighting=350
diff --git a/util/build_common.h b/util/build_common.h
index 57d055d..efb5962 100644
--- a/util/build_common.h
+++ b/util/build_common.h
@@ -104,11 +104,10 @@ bool CheckDependencies(const char *applicationName) {
 	}
 
 	for (int i = 0; !needsRebuild && i < arrlen(dependencies.files); i++) {
-		struct stat s;
-
-		// printf("%s, %s\n", applicationName, dependencies.files[i]);
+		struct stat s = { 0 };
 
 		if (stat(dependencies.files[i], &s) || s.st_mtime > dependencies.timeStamp) {
+			// printf("%s, %s, %ld, %ld\n", applicationName, dependencies.files[i], s.st_mtime, dependencies.timeStamp);
 			needsRebuild = true;
 			break;
 		}
@@ -171,6 +170,7 @@ void ParseDependencies(const char *dependencyFile, const char *applicationName,
 	struct stat s;
 
 	if (stat(dependencyFile, &s) == 0) {
+		// printf("%s %ld %ld\n", applicationName, buildStartTimeStamp, s.st_mtime);
 		list.timeStamp = s.st_mtime;
 		if (buildStartTimeStamp < s.st_mtime) list.timeStamp = buildStartTimeStamp;
 		list.optimised = _optimisationsEnabled;
diff --git a/util/header_generator.c b/util/header_generator.c
index 4a2bf5f..25a27a1 100644
--- a/util/header_generator.c
+++ b/util/header_generator.c
@@ -1190,7 +1190,9 @@ void OutputZig(Entry *root) {
 }
 
 int HeaderGeneratorMain(int argc, char **argv) {
-	if (argc < 2) {
+	bool system = argc == 3 && 0 == strcmp(argv[1], "system");
+
+	if (system) {
 		outputDependencies = FileOpen(DEST_DEPENDENCIES ".tmp", 'w');
 		FilePrintFormat(outputDependencies, ": \n");
 	}
@@ -1204,7 +1206,7 @@ int HeaderGeneratorMain(int argc, char **argv) {
 		language = argv[1];
 		output = FileOpen(argv[2], 'w');
 
-		if (0 == strcmp(argv[1], "system")) {
+		if (system) {
 			outputAPIArray = FileOpen(DEST_API_ARRAY, 'w');
 			outputSyscallArray = FileOpen(DEST_SYSCALL_ARRAY, 'w');
 			outputEnumStringsArray = FileOpen(DEST_ENUM_STRINGS_ARRAY, 'w');
@@ -1319,7 +1321,7 @@ int HeaderGeneratorMain(int argc, char **argv) {
 		Log("Unsupported language '%s'.\nLanguage must be one of: 'c', 'odin'.\n", language);
 	}
 
-	if (argc < 2) {
+	if (system) {
 		rename(DEST_DEPENDENCIES ".tmp", DEST_DEPENDENCIES);
 	}