diff --git a/redo/migrated/ui_windows.h b/redo/migrated/ui_windows.h
index d0699812..4d69b2d0 100644
--- a/redo/migrated/ui_windows.h
+++ b/redo/migrated/ui_windows.h
@@ -16,8 +16,9 @@ _UI_EXTERN void uiWIndowsUtilShow(HWND hwnd);
 _UI_EXTERN void uiWindowsUtilHide(HWND hwnd);
 _UI_EXTERN void uiWIndowsUtilEnable(HWND hwnd);
 _UI_EXTERN void uiWindowsUtilDisable(HWND hwnd);
-_UI_EXTERN void uiWindowsUtilSysFunc(HWND hwnd, uiControlSysFuncParams *p);
-_UI_EXTERN int uiWindowsUtilStartZOrder(HWND hwnd, uiControlSysFuncParams *p);
+_UI_EXTERN uintptr_t uiWindowsUtilStartZOrder(HWND hwnd);
+_UI_EXTERN uintptr_t uiWindowsUtilSetZOrder(HWND hwnd, uintptr_t insertAfter);
+_UI_EXTERN int uiWindowsUtilHasTabStops(HWND hwnd);
 _UI_EXTERN uiControl *uiWindowsNewSingleHWNDControl(uintmax_t type);
 
 // This contains the Windows-specific parts of the uiSizing structure.
@@ -45,25 +46,4 @@ _UI_EXTERN intmax_t uiWindowsWindowTextWidth(HWND hwnd);
 _UI_EXTERN char *uiWindowsControlText(uiControl *);
 _UI_EXTERN void uiWindowsControlSetText(uiControl *, const char *);
 
-struct uiControlSysFuncParams {
-	int Func;
-	BOOL HasTabStops;
-	HWND InsertAfter;
-};
-
-enum {
-	// These should enable and disable the uiControl while preserving the user enable/disable setting.
-	// These are needed because while disabling a parent window does cause children to stop receiving events, they are not shown as disabled, which is not what we want.
-	uiWindowsSysFuncContainerEnable,
-	uiWindowsSysFuncContainerDisable,
-	// This is interpreted by controls that are tab stops; the control should set HasTabStops to TRUE if so, and *LEAVE IT ALONE* if not.
-	// You only need this if implementing your own uiControl.
-	// Controls created with uiWindowsMakeControl() check for the window being enabled and the presence of WS_TABSTOP.
-	// The name is "has tab stops" because it is used by uiTabs to say "does the current tab page have tab stops?".
-	uiWindowsSysFuncHasTabStops,
-	// This tells the current control to set its Z order to be after the control in the InsertAfter field.
-	// You should also set your own handle to the InsertAfter field for the next control.
-	uiWindowsSysFuncSetZOrder,
-};
-
 #endif
diff --git a/redo/windows/control.c b/redo/windows/control.c
index d6113cf6..2efb0e72 100644
--- a/redo/windows/control.c
+++ b/redo/windows/control.c
@@ -106,29 +106,7 @@ static void singleHWNDCommitDisable(uiControl *c)
 	uiWindowsUtilDisable(HWND(c));
 }
 
-void uiWindowsUtilSysFunc(HWND hwnd, uiControlSysFuncParams *p)
-{
-	switch (p->Func) {
-	case uiControlSysFuncNop:
-		return;
-	case uiWindowsSysFuncHasTabStops:
-		if ((getStyle(hwnd) & WS_TABSTOP) != 0)
-			p->HasTabStops = TRUE;
-		return;
-	case uiWindowsSysFuncSetZOrder:
-		setWindowInsertAfter(hwnd, p->InsertAfter);
-		p->InsertAfter = hwnd;
-		return;
-	}
-	complain("unknown uiControlSysFunc() function %d in uiWindowsUtilSysFunc()", p->Func);
-}
-
-static void singleHWNDSysFunc(uiControl *c, uiControlSysFuncParams *p)
-{
-	uiWindowsUtilSysFunc(HWND(c), p);
-}
-
-int uiWindowsUtilStartZOrder(HWND hwnd, uiControlSysFuncParams *p)
+uintptr_t uiWindowsUtilStartZOrder(HWND hwnd)
 {
 	HWND insertAfter;
 
@@ -136,13 +114,33 @@ int uiWindowsUtilStartZOrder(HWND hwnd, uiControlSysFuncParams *p)
 	insertAfter = GetWindow(hwnd, GW_HWNDPREV);
 	if (insertAfter == NULL)
 		logLastError("error getting insert after window in uiWindowsUtilStartZOrder()");
-	p->InsertAfter = insertAfter;
-	return 1;
+	return (uintptr_t) insertAfter;
 }
 
-static int singleHWNDStartZOrder(uiControl *c, uiControlSysFuncParams *p)
+static uintptr_t singleHWNDStartZOrder(uiControl *c)
 {
-	return uiWindowsUtilStartZOrder(HWND(c), p);
+	return uiWindowsUtilStartZOrder(HWND(c));
+}
+
+uintptr_t uiWindowsUtilSetZOrder(HWND hwnd, uintptr_t insertAfter)
+{
+	setWindowInsertAfter(hwnd, (HWND) insertAfter);
+	return (uintptr_t) hwnd;
+}
+
+static uintptr_t singleHWNDSetZOrder(uiControl *c, uintptr_t insertAfter)
+{
+	return uiWindowsUtilSetZOrder(HWND(c), insertAfter);
+}
+
+int uiWindowsUtilHasTabStops(HWND hwnd)
+{
+	return (getStyle(hwnd) & WS_TABSTOP) != 0;
+}
+
+static int singleHWNDHasTabStops(uiControl *c)
+{
+	return uiWindowsUtilHasTabStops(HWND(c));
 }
 
 void setSingleHWNDFuncs(uiControl *c)
@@ -155,8 +153,9 @@ void setSingleHWNDFuncs(uiControl *c)
 	uiControl(c)->CommitHide = singleHWNDCommitHide;
 	uiControl(c)->CommitEnable = singleHWNDCommitEnable;
 	uiControl(c)->CommitDisable = singleHWNDCommitDisable;
-	uiControl(c)->SysFunc = singleHWNDSysFunc;
 	uiControl(c)->StartZOrder = singleHWNDStartZOrder;
+	uiControl(c)->SetZOrder = singleHWNDSetZOrder;
+	uiControl(c)->HasTabStops = singleHWNDHasTabStops;
 }
 
 uiControl *uiWindowsNewSingleHWNDControl(uintmax_t type)