Fixed Comboboxes on Mac OS X having an initial selection. This also lays the groundwork for adding Combobox/Listbox.Select() as a public function...

combobox.go

@@ -145,6 +145,8 @@ func (c *Combobox) make(window *sysData) (err error) {
 	for _, s := range c.initItems {
 		c.sysData.append(s)
 	}
+	// some platforms automatically select an item; undo that
+	c.sysData.selectIndex(-1)
 	c.created = true
 	return nil
 }

sysdata.go

@@ -40,6 +40,7 @@ var _xSysData interface {
 	setProgress(int)
 	len() int
 	setAreaSize(int, int)
+	selectIndex(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

@@ -33,6 +33,7 @@ type classData struct {
 	selTexts		func(id C.id) []string
 	delete		func(id C.id, index int)
 	len			func(id C.id) int
+	selectIndex	func(id C.id, index int, alternate bool)
 }
 
 var (
@@ -82,6 +83,8 @@ var (
 	_setIndeterminate = sel_getUid("setIndeterminate:")
 	_setDoubleValue = sel_getUid("setDoubleValue:")
 	_numberOfItems = sel_getUid("numberOfItems")
+	_selectItemAtIndex = sel_getUid("selectItemAtIndex:")
+	_deselectItemAtIndex = sel_getUid("deselectItemAtIndex:")
 )
 
 // because the only way to make a new NSControl/NSView is with a frame (it gets overridden later)
@@ -238,6 +241,22 @@ var classTypes = [nctypes]*classData{
 		len:			func(id C.id) int {
 			return int(C.objc_msgSend_intret_noargs(id, _numberOfItems))
 		},
+		selectIndex:	func(id C.id, index int, alternate bool) {
+			// NSPopUpButton makes this easy
+			if !alternate {
+				C.objc_msgSend_int(id, _selectItemAtIndex, C.intptr_t(index))
+				return
+			}
+			// NSComboBox doesn't document that we can do [cb selectItemAtIndex:-1], so we have to do this to be safe
+			if index == -1 {
+				idx := C.objc_msgSend_intret_noargs(id, _indexOfSelectedItem)
+				if idx != -1 {
+					C.objc_msgSend_int(id, _deselectItemAtIndex, idx)
+				}
+				return
+			}
+			C.objc_msgSend_int(id, _selectItemAtIndex, C.intptr_t(index))
+		},
 	},
 	c_lineedit:		&classData{
 		make:		func(parentWindow C.id, alternate bool) C.id {
@@ -542,3 +561,13 @@ func (s *sysData) setAreaSize(width int, height int) {
 	}
 	<-ret
 }
+
+func (s *sysData) selectIndex(index int) {
+	ret := make(chan struct{})
+	defer close(ret)
+	uitask <- func() {
+		classTypes[s.ctype].selectIndex(s.id, index, s.alternate)
+		ret <- struct{}{}
+	}
+	<-ret
+}

sysdata_unix.go

@@ -359,3 +359,7 @@ func (s *sysData) setAreaSize(width int, height int) {
 	}
 	<-ret
 }
+
+func (s *sysData) selectIndex(index int) {
+	// TODO not yet implemented on Unix (added for Mac only right now)
+}

sysdata_windows.go

@@ -641,3 +641,7 @@ func (s *sysData) setAreaSize(width int, height int) {
 	}
 	<-ret
 }
+
+func (s *sysData) selectIndex(index int) {
+	// TODO not yet implemented on Windows (added for Mac only right now)
+}

todo.md

@@ -1,7 +1,5 @@
 important things:
-- NSPopUpButton does allow no initial selection ([b setSelectedIndex:-1]); use it
-	- need to use it /after/ adding initial items, otherwise it won't work
-	- find out if I can do the same with the ListBoxes
+- NSTableViews start out with an initial selection (which is against our docs)
 - NSComboBox scans the entered text to see if it matches one of the items and returns the index of that item if it does; find out how to suppress this so that it returns -1 unless the item was chosen from the list (like the other platforms)
 - some Cocoa controls don't seem to resize correctly: Buttons have space around the edges
 - LineEdit heights on Windows seem too big; either that or LineEdit, Button, and Label text is not vertically centered properly