diff --git a/ui_darwin.h b/ui_darwin.h
index ffd7c9c9..e70cd94a 100644
--- a/ui_darwin.h
+++ b/ui_darwin.h
@@ -16,20 +16,12 @@ struct uiDarwinControl {
 	uiControl c;
 	void (*Relayout)(uiDarwinControl *);
 };
-_UI_EXTERN uintmax_t uiDarwinControlType(void);
-#define uiDarwinControl(this) ((uiDarwinControl *) uiIsA((this), uiDarwinControlType(), 1))
+#define uiDarwinControl(this) ((uiDarwinControl *) (this))
 // TODO document
 _UI_EXTERN void uiDarwinControlTriggerRelayout(uiDarwinControl *);
 
 // TODO document
-#define uiDarwinDefineControlWithOnDestroy(type, typefn, handlefield, onDestroy) \
-	static uintmax_t _ ## type ## Type = 0; \
-	uintmax_t typefn(void) \
-	{ \
-		if (_ ## type ## Type == 0) \
-			_ ## type ## Type = uiRegisterType(#type, uiDarwinControlType(), sizeof (type)); \
-		return _ ## type ## Type; \
-	} \
+#define uiDarwinDefineControlWithOnDestroy(type, handlefield, onDestroy) \
 	static void _ ## type ## CommitDestroy(uiControl *c) \
 	{ \
 		type *this = type(c); \
@@ -49,8 +41,8 @@ _UI_EXTERN void uiDarwinControlTriggerRelayout(uiDarwinControl *);
 		/* do nothing */ \
 	}
 
-#define uiDarwinDefineControl(type, typefn, handlefield) \
-	uiDarwinDefineControlWithOnDestroy(type, typefn, handlefield, (void) this;)
+#define uiDarwinDefineControl(type, handlefield) \
+	uiDarwinDefineControlWithOnDestroy(type, handlefield, (void) this;)
 
 #define uiDarwinFinishNewControl(variable, type) \
 	uiControl(variable)->CommitDestroy = _ ## type ## CommitDestroy; \
diff --git a/ui_haiku.hpp b/ui_haiku.hpp
index 246d377d..bd2ae9c5 100644
--- a/ui_haiku.hpp
+++ b/ui_haiku.hpp
@@ -17,18 +17,10 @@ typedef struct uiHaikuControl uiHaikuControl;
 struct uiHaikuControl {
 	uiControl c;
 };
-_UI_EXTERN uintmax_t uiHaikuControlType(void);
-#define uiHaikuControl(this) ((uiHaikuControl *) uiIsA((this), uiHaikuControlType(), 1))
+#define uiHaikuControl(this) ((uiHaikuControl *) (this))
 
 // TODO document
-#define uiHaikuDefineControlWithOnDestroy(type, typefn, handlefield, onDestroy) \
-	static uintmax_t _ ## type ## Type = 0; \
-	uintmax_t typefn(void) \
-	{ \
-		if (_ ## type ## Type == 0) \
-			_ ## type ## Type = uiRegisterType(#type, uiHaikuControlType(), sizeof (type)); \
-		return _ ## type ## Type; \
-	} \
+#define uiHaikuDefineControlWithOnDestroy(type, handlefield, onDestroy) \
 	static void _ ## type ## CommitDestroy(uiControl *c) \
 	{ \
 		type *hthis = type(c); \
@@ -44,8 +36,8 @@ _UI_EXTERN uintmax_t uiHaikuControlType(void);
 		/* do nothing */ \
 	}
 
-#define uiHaikuDefineControl(type, typefn, handlefield) \
-	uiHaikuDefineControlWithOnDestroy(type, typefn, handlefield, (void) hthis;)
+#define uiHaikuDefineControl(type, handlefield) \
+	uiHaikuDefineControlWithOnDestroy(type, handlefield, (void) hthis;)
 
 #define uiHaikuFinishNewControl(variable, type) \
 	uiControl(variable)->CommitDestroy = _ ## type ## CommitDestroy; \
diff --git a/ui_unix.h b/ui_unix.h
index f41a1301..75b14ac8 100644
--- a/ui_unix.h
+++ b/ui_unix.h
@@ -15,18 +15,10 @@ typedef struct uiUnixControl uiUnixControl;
 struct uiUnixControl {
 	uiControl c;
 };
-_UI_EXTERN uintmax_t uiUnixControlType(void);
-#define uiUnixControl(this) ((uiUnixControl *) uiIsA((this), uiUnixControlType(), 1))
+#define uiUnixControl(this) ((uiUnixControl *) (this))
 
 // TODO document
-#define uiUnixDefineControlWithOnDestroy(type, typefn, onDestroy) \
-	static uintmax_t _ ## type ## Type = 0; \
-	uintmax_t typefn(void) \
-	{ \
-		if (_ ## type ## Type == 0) \
-			_ ## type ## Type = uiRegisterType(#type, uiUnixControlType(), sizeof (type)); \
-		return _ ## type ## Type; \
-	} \
+#define uiUnixDefineControlWithOnDestroy(type, onDestroy) \
 	static void _ ## type ## CommitDestroy(uiControl *c) \
 	{ \
 		type *this = type(c); \
@@ -42,8 +34,8 @@ _UI_EXTERN uintmax_t uiUnixControlType(void);
 		/* do nothing */ \
 	}
 
-#define uiUnixDefineControl(type, typefn) \
-	uiUnixDefineControlWithOnDestroy(type, typefn, (void) this;)
+#define uiUnixDefineControl(type) \
+	uiUnixDefineControlWithOnDestroy(type, (void) this;)
 
 #define uiUnixFinishNewControl(variable, type) \
 	uiControl(variable)->CommitDestroy = _ ## type ## CommitDestroy; \
diff --git a/ui_windows.h b/ui_windows.h
index 2fe6aad0..099b7f84 100644
--- a/ui_windows.h
+++ b/ui_windows.h
@@ -22,20 +22,12 @@ struct uiWindowsControl {
 	void (*AssignControlIDZOrder)(uiWindowsControl *, LONG_PTR *, HWND *);
 	void (*ArrangeChildrenControlIDsZOrder)(uiWindowsControl *);
 };
-_UI_EXTERN uintmax_t uiWindowsControlType(void);
-#define uiWindowsControl(this) ((uiWindowsControl *) uiIsA((this), uiWindowsControlType(), 1))
+#define uiWindowsControl(this) ((uiWindowsControl *) (this))
 // TODO document
 _UI_EXTERN void uiWindowsControlQueueRelayout(uiWindowsControl *);
 
 // TODO document
-#define uiWindowsDefineControlWithOnDestroy(type, typefn, onDestroy) \
-	static uintmax_t _ ## type ## Type = 0; \
-	uintmax_t typefn(void) \
-	{ \
-		if (_ ## type ## Type == 0) \
-			_ ## type ## Type = uiRegisterType(#type, uiWindowsControlType(), sizeof (type)); \
-		return _ ## type ## Type; \
-	} \
+#define uiWindowsDefineControlWithOnDestroy(type, onDestroy) \
 	static void _ ## type ## CommitDestroy(uiControl *c) \
 	{ \
 		type *me = type(c); \
@@ -70,8 +62,8 @@ _UI_EXTERN void uiWindowsControlQueueRelayout(uiWindowsControl *);
 		/* do nothing */ \
 	}
 
-#define uiWindowsDefineControl(type, typefn) \
-	uiWindowsDefineControlWithOnDestroy(type, typefn, (void) me;)
+#define uiWindowsDefineControl(type) \
+	uiWindowsDefineControlWithOnDestroy(type, (void) me;)
 
 #define uiWindowsFinishNewControl(variable, type) \
 	uiControl(variable)->CommitDestroy = _ ## type ## CommitDestroy; \