Controls that support deletion need to provide the number of children they contain for error detection

darwin/box.m

@@ -37,6 +37,7 @@
 - (CGFloat)paddingAmount;
 - (void)establishOurConstraints;
 - (void)append:(uiControl *)c stretchy:(int)stretchy;
+- (int)countChildren;
 - (void)delete:(int)n;
 - (int)isPadded;
 - (void)setPadded:(int)p;
@@ -292,6 +293,11 @@ struct uiBox {
 	[bc release];		// we don't need the initial reference now
 }
 
+- (int)countChildren
+{
+	return (int) [self->children count];
+}
+
 - (void)delete:(int)n
 {
 	boxChild *bc;
@@ -423,6 +429,11 @@ static void uiBoxChildVisibilityChanged(uiDarwinControl *c)
 	[b->view establishOurConstraints];
 }
 
+int uiBoxNumChildren(uiBox *b)
+{
+	return [b->view countChildren];
+}
+
 void uiBoxAppend(uiBox *b, uiControl *c, int stretchy)
 {
 	// LONGTERM on other platforms

darwin/form.m

@@ -39,6 +39,7 @@
 - (CGFloat)paddingAmount;
 - (void)establishOurConstraints;
 - (void)append:(NSString *)label c:(uiControl *)c stretchy:(int)stretchy;
+- (int)countChildren;
 - (void)delete:(int)n;
 - (int)isPadded;
 - (void)setPadded:(int)p;
@@ -394,6 +395,11 @@ struct uiForm {
 	[fc release];		// we don't need the initial reference now
 }
 
+- (int)countChildren
+{
+	return (int) [self->children count];
+}
+
 - (void)delete:(int)n
 {
 	formChild *fc;
@@ -534,6 +540,11 @@ void uiFormAppend(uiForm *f, const char *label, uiControl *c, int stretchy)
 	[f->view append:toNSString(label) c:c stretchy:stretchy];
 }
 
+int uiFormNumChildren(uiForm *f)
+{
+	return [f->view countChildren];
+}
+
 void uiFormDelete(uiForm *f, int n)
 {
 	[f->view delete:n];

ui.h

@@ -123,6 +123,7 @@ _UI_EXTERN uiButton *uiNewButton(const char *text);
 typedef struct uiBox uiBox;
 #define uiBox(this) ((uiBox *) (this))
 _UI_EXTERN void uiBoxAppend(uiBox *b, uiControl *child, int stretchy);
+_UI_EXTERN int uiBoxNumChildren(uiBox *b);
 _UI_EXTERN void uiBoxDelete(uiBox *b, int index);
 _UI_EXTERN int uiBoxPadded(uiBox *b);
 _UI_EXTERN void uiBoxSetPadded(uiBox *b, int padded);
@@ -657,6 +658,7 @@ _UI_EXTERN uiColorButton *uiNewColorButton(void);
 typedef struct uiForm uiForm;
 #define uiForm(this) ((uiForm *) (this))
 _UI_EXTERN void uiFormAppend(uiForm *f, const char *label, uiControl *c, int stretchy);
+_UI_EXTERN int uiFormNumChildren(uiForm *f);
 _UI_EXTERN void uiFormDelete(uiForm *f, int index);
 _UI_EXTERN int uiFormPadded(uiForm *f);
 _UI_EXTERN void uiFormSetPadded(uiForm *f, int padded);

unix/box.c

@@ -47,6 +47,11 @@ static void uiBoxDestroy(uiControl *c)
 	uiFreeControl(uiControl(b));
 }
 
+int uiBoxNumChildren(uiBox *b)
+{
+	return (int) b->controls->len;
+}
+
 void uiBoxAppend(uiBox *b, uiControl *c, int stretchy)
 {
 	struct boxChild bc;

unix/form.c

@@ -101,6 +101,11 @@ void uiFormAppend(uiForm *f, const char *label, uiControl *c, int stretchy)
 		NULL);
 }
 
+int uiFormNumChildren(uiForm *f)
+{
+	return (int) f->children->len;
+}
+
 void uiFormDelete(uiForm *f, int index)
 {
 	struct formChild *fc;

windows/box.cpp

@@ -254,6 +254,11 @@ static void boxArrangeChildren(uiBox *b)
 		uiWindowsControlAssignControlIDZOrder(uiWindowsControl(bc.c), &controlID, &insertAfter);
 }
 
+int uiBoxNumChildren(uiBox *b)
+{
+	return (int) b->controls->size();
+}
+
 void uiBoxAppend(uiBox *b, uiControl *c, int stretchy)
 {
 	struct boxChild bc;

windows/form.cpp

@@ -276,6 +276,11 @@ void uiFormAppend(uiForm *f, const char *label, uiControl *c, int stretchy)
 	uiWindowsControlMinimumSizeChanged(uiWindowsControl(f));
 }
 
+int uiFormNumChildren(uiForm *f)
+{
+	return (int) f->controls->size();
+}
+
 void uiFormDelete(uiForm *f, int index)
 {
 	struct formChild fc;