Found a method in NSArrayController via Stack Overflow which lets me suppress selection-changing behavior on NSTableView inserts; use that on Listbox in Mac OS X. This means sysData.selectIndices() and its Mac OS X implementation can (and has) gone away, clearing TODOs on Windows and Unix by extension.

listbox.go

@@ -146,8 +146,6 @@ func (l *Listbox) make(window *sysData) (err error) {
 	for _, s := range l.initItems {
 		l.sysData.append(s)
 	}
-	// some platforms automatically select an item; undo that
-	l.sysData.selectIndices(nil)
 	l.created = true
 	return nil
 }

listbox_darwin.go

@@ -217,12 +217,3 @@ func listboxDelete(listbox C.id, index int) {
 func listboxLen(listbox C.id) int {
 	return int(C.listboxLen(listboxInScrollView(listbox)))
 }
-
-func listboxSelectIndices(id C.id, indices []int) {
-	listbox := listboxInScrollView(id)
-	if len(indices) == 0 {
-		C.listboxDeselectAll(listbox)
-		return
-	}
-	panic("selectListboxIndices() > 0 not yet implemented (TODO)")
-}

listbox_darwin.m

@@ -37,6 +37,10 @@ id makeListboxArray(void)
 
 	ac = [NSArrayController new];
 	[ac setAutomaticallyRearrangesObjects:NO];
+	// we don't want Cocoa to change the selection when items are inserted
+	// found via TODO_get_Stack_Overflow_link; not sure how I missed it the first time
+	[ac setSelectsInsertedObjects:NO];
+	// TODO figure out how to inhibit this behavior on delete
 	return ac;
 }
 
@@ -136,8 +140,3 @@ intptr_t listboxLen(id listbox)
 {
 	return fromNSInteger([toNSTableView(listbox) numberOfRows]);
 }
-
-void listboxDeselectAll(id listbox)
-{
-	[toNSTableView(listbox) deselectAll:listbox];
-}

objc_darwin.h

@@ -79,7 +79,6 @@ extern uintptr_t listboxIndexesCount(id);
 extern uintptr_t listboxIndexesFirst(id);
 extern uintptr_t listboxIndexesNext(id, uintptr_t);
 extern intptr_t listboxLen(id);
-extern void listboxDeselectAll(id);
 
 /* prefsize_darwin.m */
 extern struct xsize controlPrefSize(id);

sysdata.go

@@ -41,7 +41,6 @@ var _xSysData interface {
 	len() int
 	setAreaSize(int, int)
 	selectIndex(int)
-	selectIndices([]int)
 } = &sysData{}		// this line will error if there's an inconsistency
 
 // signal sends the event signal. This raise is done asynchronously to avoid deadlocking the UI task.

sysdata_darwin.go

@@ -33,7 +33,6 @@ type classData struct {
 	delete		func(id C.id, index int)
 	len			func(id C.id) int
 	selectIndex	func(id C.id, index int, alternate bool)
-	selectIndices	func(id C.id, indices []int)
 }
 
 func addControl(parentWindow C.id, control C.id) {
@@ -183,7 +182,6 @@ var classTypes = [nctypes]*classData{
 		selTexts:		listboxSelectedTexts,
 		delete:		listboxDelete,
 		len:			listboxLen,
-		selectIndices:	listboxSelectIndices,
 	},
 	c_progressbar:		&classData{
 		make:		func(parentWindow C.id, alternate bool, s *sysData) C.id {
@@ -419,13 +417,3 @@ func (s *sysData) selectIndex(index int) {
 	}
 	<-ret
 }
-
-func (s *sysData) selectIndices(indices []int) {
-	ret := make(chan struct{})
-	defer close(ret)
-	uitask <- func() {
-		classTypes[s.ctype].selectIndices(s.id, indices)
-		ret <- struct{}{}
-	}
-	<-ret
-}

sysdata_unix.go

@@ -364,7 +364,3 @@ func (s *sysData) setAreaSize(width int, height int) {
 func (s *sysData) selectIndex(index int) {
 	// TODO not yet implemented on Unix (added for Mac only right now)
 }
-
-func (s *sysData) selectIndices(indices []int) {
-	// TODO not yet implemented on Windows (added for Mac only right now)
-}

sysdata_windows.go

@@ -646,7 +646,3 @@ func (s *sysData) setAreaSize(width int, height int) {
 func (s *sysData) selectIndex(index int) {
 	// TODO not yet implemented on Windows (added for Mac only right now)
 }
-
-func (s *sysData) selectIndices(indices []int) {
-	// TODO not yet implemented on Windows (added for Mac only right now)
-}