Cleaned out some of that gunk. I can't avoid subclassing the standard controls, but making it so that the uiControl returned by uiDarwinNewControl() can be freed by the caller will help.

new/button_darwin.m

@@ -1,7 +1,7 @@
 // 7 april 2015
 #import "uipriv_darwin.h"
 
-@interface uiNSButton : NSButton <uiFreeOnDealloc>
+@interface uiNSButton : NSButton
 @property uiControl *uiC;
 @property void (*uiOnClicked)(uiControl *, void *);
 @property void *uiOnClickedData;
@@ -10,12 +10,15 @@
 
 @implementation uiNSButton
 
-uiLogObjCClassAllocations(uiDoFreeOnDealloc(self.uiFreeList);)
+- (void)dealloc
-uiFreeOnDeallocImpl
+{
+	uiDarwinControlFree(self.uiC);
+	[super dealloc];
+}
 
 - (IBAction)uiButtonClicked:(id)sender
 {
-	(*(self.onClicked))(self.c, self.onClickedData);
+	(*(self.uiOnClicked))(self.uiC, self.uiOnClickedData);
 }
 
 @end
@@ -33,7 +36,7 @@ uiControl *uiNewButton(const char *text)
 
 	c = uiDarwinNewControl([uiNSButton class], NO, NO, NULL);
 	b = (uiNSButton *) uiControlHandle(c);
-	b.c = c;
+	b.uiC = c;
 
 	[b setTitle:toNSString(text)];
 	[b setButtonType:NSMomentaryPushInButton];
@@ -44,7 +47,7 @@ uiControl *uiNewButton(const char *text)
 	[b setTarget:b];
 	[b setAction:@selector(uiButtonClicked:)];
 
-	b.onClicked = defaultOnClicked;
+	b.uiOnClicked = defaultOnClicked;
 
 	return b.c;
 }
@@ -56,6 +59,6 @@ void uiButtonOnClicked(uiControl *c, void (*f)(uiControl *, void *), void *data)
 	button *b;
 
 	b = (uiNSButton *) uiControlHandle(c);
-	b.onClicked = f;
+	b.uiOnClicked = f;
-	b.onClickedData = data;
+	b.uiOnClickedData = data;
 }

new/init_darwin.m

@@ -6,8 +6,6 @@
 
 @implementation uiApplication
 
-uiLogObjCClassAllocations()
-
 // hey look! we're overriding terminate:!
 // we're going to make sure we can go back to main() whether Cocoa likes it or not!
 // and just how are we going to do that, hm?

new/newcontrol_darwin.m

@@ -8,7 +8,6 @@ struct uiSingleViewControl {
 	NSView *view;
 	NSScrollView *scrollView;
 	NSView *immediate;		// the control that is added to the parent container; either view or scrollView
-	void *data;
 };
 
 #define S(c) ((uiSingleViewControl *) (c))
@@ -59,12 +58,9 @@ static void singleResize(uiControl *c, intmax_t x, intmax_t y, intmax_t width, i
 	[S(c)->immediate setFrame:frame];
 }
 
-// TODO connect free function
+uiControl *uiDarwinNewControl(Class class, BOOL inScrollView, BOOL scrollViewHasBorder)
-
-uiControl *uiDarwinNewControl(Class class, BOOL inScrollView, BOOL scrollViewHasBorder, void *data)
 {
 	uiSingleViewControl *c;
-	uiFreeOnDealloc *freer;
 
 	c = uiNew(uiSingleViewControl);
 	// thanks to autoxr and arwyn in irc.freenode.net/#macdev
@@ -91,15 +87,10 @@ uiControl *uiDarwinNewControl(Class class, BOOL inScrollView, BOOL scrollViewHas
 	c->control.preferredSize = singlePreferredSize;
 	c->control.resize = singleResize;
 
-	c->data = data;
-
-	freer = (uiFreeOnDealloc *) (c->view);
-	[freer uiFreeOnDealloc:c];
-
 	return (uiControl *) c;
 }
 
-void *uiDarwinControlData(uiControl *c)
+void uiDarwinControlFree(uiControl *c)
 {
-	return S(c)->data;
+	uiFree(c);
 }

new/ui_darwin.h

@@ -10,8 +10,8 @@ This file assumes that you have imported <Cocoa/Cocoa.h> and "ui.h" beforehand.
 // uiDarwinNewControl() creates a new uiControl with the given Cocoa control inside.
 // The first parameter should come from [RealControlType class].
 // The two scrollView parameters allow placing scrollbars on the new control.
-// The data parameter can be accessed with uiDarwinControlData().
+// Your control must call uiDarwinControlFree() on the returned uiControl in its -[dealloc] method.
-extern uiControl *uiDarwinNewControl(Class class, BOOL inScrollView, BOOL scrollViewHasBorder, void *data);
+extern uiControl *uiDarwinNewControl(Class class, BOOL inScrollView, BOOL scrollViewHasBorder);
-extern void *uiDarwinControlData(uiControl *c);
+extern void uiDarwinControlFree(uiControl *);
 
 #endif

new/uipriv_darwin.h

@@ -39,17 +39,6 @@ struct uiSizing {
 
 // util_darwin.m
 extern void setStandardControlFont(NSControl *);
-@protocol uiFreeOnDealloc
-- (void)uiFreeOnDealloc:(void *)p;
-@end
-#define uiFreeOnDeallocImpl \
-- (void)uiFreeOnDealloc:(void *)p \
-{ \
-	if (self.uiFreeList == nil) \
-		self.uiFreeList = [NSMutableArray new]; \
-	[self.uiFreeList addObject:[NSValue valueWIthPointer:p]]; \
-}
-extern void uiDoFreeOnDealloc(NSMutableArray *);
 
 // container_darwin.m
 @interface uiContainer : NSView

new/util_darwin.m

@@ -6,13 +6,3 @@ void setStandardControlFont(NSControl *control)
 {
 	[control setFont:[NSFont systemFontOfSize:[NSFont systemFontSizeForControlSize:NSRegularControlSize]]];
 }
-
-void uiDoFreeOnDealloc(NSMutableArray *m)
-{
-	[m enumerateObjectsUsingBlock:^(id obj, NSUInteger index, BOOL *stop) {
-		NSValue *v = (NSValue *) obj;
-
-		uiFree([v pointerValue]);
-	}];
-	[m release];
-}