diff --git a/darwin/main.m b/darwin/main.m
index 2c934330..6faef4f4 100644
--- a/darwin/main.m
+++ b/darwin/main.m
@@ -159,12 +159,13 @@ void uiMain(void)
 	[realNSApp() run];
 }
 
-void uiMainSteps(void)
+void uiMainSteps(void (*f)(void *), void *data)
 {
 	isRunning = ^{
 		return stepsIsRunning;
 	};
 	stepsIsRunning = YES;
+	(*f)(data);
 }
 
 // see also:
diff --git a/test/main.c b/test/main.c
index 803326b5..e69feee7 100644
--- a/test/main.c
+++ b/test/main.c
@@ -39,6 +39,12 @@ uiTab *mainTab;
 uiBox *(*newhbox)(void);
 uiBox *(*newvbox)(void);
 
+static void stepsLoop(void *data)
+{
+	while (uiMainStep(1))
+		;
+}
+
 int main(int argc, char *argv[])
 {
 	uiInitOptions o;
@@ -161,11 +167,8 @@ int main(int argc, char *argv[])
 	uiControlShow(uiControl(w));
 	if (!steps)
 		uiMain();
-	else {
-		uiMainSteps();
-		while (uiMainStep(1))
-			;
-	}
+	else
+		uiMainSteps(stepsLoop, NULL);
 	printf("after uiMain()\n");
 	uiUninit();
 	printf("after uiUninit()\n");
diff --git a/ui.h b/ui.h
index 6b7a1e8b..4fdd9e3e 100644
--- a/ui.h
+++ b/ui.h
@@ -45,7 +45,7 @@ _UI_EXTERN void uiUninit(void);
 _UI_EXTERN void uiFreeInitError(const char *err);
 
 _UI_EXTERN void uiMain(void);
-_UI_EXTERN void uiMainSteps(void);
+_UI_EXTERN void uiMainSteps(void (*f)(void *), void *data);
 _UI_EXTERN int uiMainStep(int wait);
 _UI_EXTERN void uiQuit(void);