Removed error returns from Combobox.Delete(), Listbox.Delete(), and sysData.delete(), since they are no longer used. Updated the TODO file to mark this issue closed.

combobox.go

@@ -78,7 +78,7 @@ badrange:
 }
 
 // Delete removes the given item from the Combobox. It panics if the given index is out of bounds.
-func (c *Combobox) Delete(index int) error {
+func (c *Combobox) Delete(index int) {
 	c.lock.Lock()
 	defer c.lock.Unlock()
 
@@ -86,13 +86,14 @@ func (c *Combobox) Delete(index int) error {
 		if index < 0 || index >= c.sysData.len() {
 			goto badrange
 		}
-		return c.sysData.delete(index)
+		c.sysData.delete(index)
+		return
 	}
 	if index < 0 || index >= len(c.initItems) {
 		goto badrange
 	}
 	c.initItems = append(c.initItems[:index], c.initItems[index + 1:]...)
-	return nil
+	return
 badrange:
 	panic(fmt.Errorf("index %d out of range in Combobox.Delete()", index))
 }

listbox.go

@@ -70,7 +70,7 @@ badrange:
 }
 
 // Delete removes the given item from the Listbox. It panics if the given index is out of bounds.
-func (l *Listbox) Delete(index int) error {
+func (l *Listbox) Delete(index int) {
 	l.lock.Lock()
 	defer l.lock.Unlock()
 
@@ -78,13 +78,14 @@ func (l *Listbox) Delete(index int) error {
 		if index < 0 || index >= l.sysData.len() {
 			goto badrange
 		}
-		return l.sysData.delete(index)
+		l.sysData.delete(index)
+		return
 	}
 	if index < 0 || index >= len(l.initItems) {
 		goto badrange
 	}
 	l.initItems = append(l.initItems[:index], l.initItems[index + 1:]...)
-	return nil
+	return
 badrange:
 	panic(fmt.Errorf("index %d out of range in Listbox.Delete()", index))
 }

sysdata.go

@@ -61,7 +61,7 @@ func (c *cSysData) selectedTexts() []string {
 func (c *cSysData) setWindowSize(int, int) error {
 	panic(runtime.GOOS + " sysData does not define setWindowSize()")
 }
-func (c *cSysData) delete(int) error {
+func (c *cSysData) delete(int) {
 	panic(runtime.GOOS + " sysData does not define delete()")
 }
 func (c *cSysData) preferredSize() (int, int) {

sysdata_darwin.go

@@ -449,7 +449,7 @@ func (s *sysData) setWindowSize(width int, height int) error {
 	return nil
 }
 
-func (s *sysData) delete(index int) error {
+func (s *sysData) delete(index int) {
 	ret := make(chan struct{})
 	defer close(ret)
 	uitask <- func() {
@@ -457,7 +457,6 @@ func (s *sysData) delete(index int) error {
 		ret <- struct{}{}
 	}
 	<-ret
-	return nil
 }
 
 func (s *sysData) setProgress(percent int) {

sysdata_unix.go

@@ -275,7 +275,7 @@ func (s *sysData) setWindowSize(width int, height int) error {
 	return nil
 }
 
-func (s *sysData) delete(index int) error {
+func (s *sysData) delete(index int) {
 	ret := make(chan struct{})
 	defer close(ret)
 	uitask <- func() {
@@ -283,7 +283,6 @@ func (s *sysData) delete(index int) error {
 		ret <- struct{}{}
 	}
 	<-ret
-	return nil
 }
 
 func (s *sysData) setProgress(percent int) {

sysdata_windows.go

@@ -494,7 +494,7 @@ func (s *sysData) setWindowSize(width int, height int) error {
 	return nil
 }
 
-func (s *sysData) delete(index int) (err error) {
+func (s *sysData) delete(index int) {
 	ret := make(chan uiret)
 	defer close(ret)
 	uitask <- &uimsg{
@@ -509,9 +509,8 @@ func (s *sysData) delete(index int) (err error) {
 	}
 	r := <-ret
 	if r.ret == uintptr(classTypes[s.ctype].selectedIndexErr) {
-		return fmt.Errorf("failed to delete item from combobox/listbox (last error: %v)", r.err)
+		panic(fmt.Errorf("failed to delete item from combobox/listbox (last error: %v)", r.err))
 	}
-	return nil
 }
 
 func (s *sysData) setProgress(percent int) {

todo.md

@@ -17,8 +17,7 @@ so I don't forget:
 - Combobox/Listbox.Select (with Listbox.Select allowing bulk)
 	- Checkbox.Check or Checkbox.SetChecked
 - Listbox.SelectAll
-- have Listbox.Delete() panic on invalid index; it does not yet due to the Mac OS X signaling issue mentioned under "super important"
+- have methods that take indices panic on invalid index, like the Stack and Grid stretchy methods
-	- same for other methods that take indices, like the Stack and Grid stretchy methods
 - make the Windows implementation of message boxes run on uitask
 	- ensure MsgBoxError can run if initialization failed if things change ever
 - should Labels be selectable?