diff --git a/tracker/gioui/instrument_editor.go b/tracker/gioui/instrument_editor.go
index a851f05..3863f9d 100644
--- a/tracker/gioui/instrument_editor.go
+++ b/tracker/gioui/instrument_editor.go
@@ -84,8 +84,8 @@ func NewInstrumentEditor(model *tracker.Model) *InstrumentEditor {
 		commentEditor:       NewEditor(widget.Editor{}),
 		nameEditor:          NewEditor(widget.Editor{SingleLine: true, Submit: true, Alignment: text.Middle}),
 		searchEditor:        NewEditor(widget.Editor{SingleLine: true, Submit: true, Alignment: text.Start}),
-		commentString:       model.InstrumentComment().String(),
-		nameString:          model.InstrumentName().String(),
+		commentString:       model.InstrumentComment(),
+		nameString:          model.InstrumentName(),
 		instrumentDragList:  NewDragList(model.Instruments().List(), layout.Horizontal),
 		unitDragList:        NewDragList(model.Units().List(), layout.Vertical),
 		unitEditor:          NewUnitEditor(model),
@@ -271,7 +271,7 @@ func (ie *InstrumentEditor) layoutInstrumentHeader(gtx C, t *Tracker) D {
 					}
 					style := MaterialEditor(t.Theme, &t.Theme.InstrumentEditor.InstrumentComment, ie.commentEditor, "Comment")
 					ret := layout.UniformInset(unit.Dp(6)).Layout(gtx, style.Layout)
-					ie.commentString.Set(ie.commentEditor.Text())
+					ie.commentString.SetValue(ie.commentEditor.Text())
 					return ret
 				}),
 			)
@@ -311,7 +311,7 @@ func (ie *InstrumentEditor) layoutInstrumentList(gtx C, t *Tracker) D {
 					defer clip.Rect(image.Rect(0, 0, gtx.Constraints.Max.X, gtx.Constraints.Max.Y)).Push(gtx.Ops).Pop()
 					return style.Layout(gtx)
 				})
-				ie.nameString.Set(ie.nameEditor.Text())
+				ie.nameString.SetValue(ie.nameEditor.Text())
 				return dims
 			}
 			if name == "" {
@@ -417,7 +417,7 @@ func (ie *InstrumentEditor) layoutUnitList(gtx C, t *Tracker) D {
 			layout.Rigid(func(gtx C) D {
 				if i == ie.unitDragList.TrackerList.Selected() {
 					defer clip.Rect(image.Rect(0, 0, gtx.Constraints.Max.X, gtx.Constraints.Max.Y)).Push(gtx.Ops).Pop()
-					str := tracker.String{StringData: (*tracker.UnitSearch)(t.Model)}
+					str := t.Model.UnitSearch()
 					ie.searchEditor.SetText(str.Value())
 					for ie.searchEditor.Submitted(gtx) {
 						ie.unitDragList.Focus()
@@ -439,7 +439,7 @@ func (ie *InstrumentEditor) layoutUnitList(gtx C, t *Tracker) D {
 					}
 					style := MaterialEditor(t.Theme, &editorStyle, ie.searchEditor, "---")
 					ret := style.Layout(gtx)
-					str.Set(ie.searchEditor.Text())
+					str.SetValue(ie.searchEditor.Text())
 					return ret
 				} else {
 					text := u.Type
diff --git a/tracker/gioui/tracker.go b/tracker/gioui/tracker.go
index 81b67d0..d19e6e8 100644
--- a/tracker/gioui/tracker.go
+++ b/tracker/gioui/tracker.go
@@ -91,7 +91,7 @@ func NewTracker(model *tracker.Model) *Tracker {
 
 		Model: model,
 
-		filePathString: model.FilePath().String(),
+		filePathString: model.FilePath(),
 	}
 	t.PopupAlert = NewPopupAlert(model.Alerts())
 	var warn error
diff --git a/tracker/gioui/unit_editor.go b/tracker/gioui/unit_editor.go
index 37d7205..bd0cc19 100644
--- a/tracker/gioui/unit_editor.go
+++ b/tracker/gioui/unit_editor.go
@@ -159,14 +159,14 @@ func (pe *UnitEditor) layoutFooter(gtx C, t *Tracker) D {
 			return hintText.Layout(gtx)
 		}),
 		layout.Flexed(1, func(gtx C) D {
-			s := t.UnitComment().String()
+			s := t.UnitComment()
 			pe.commentEditor.SetText(s.Value())
 			for pe.commentEditor.Submitted(gtx) || pe.commentEditor.Cancelled(gtx) {
 				t.InstrumentEditor.Focus()
 			}
 			commentStyle := MaterialEditor(t.Theme, &t.Theme.InstrumentEditor.UnitComment, pe.commentEditor, "---")
 			ret := commentStyle.Layout(gtx)
-			s.Set(pe.commentEditor.Text())
+			s.SetValue(pe.commentEditor.Text())
 			return ret
 		}),
 	)
diff --git a/tracker/model_test.go b/tracker/model_test.go
index 65ab4bc..ca6f03e 100644
--- a/tracker/model_test.go
+++ b/tracker/model_test.go
@@ -71,10 +71,10 @@ func (s *modelFuzzState) Iterate(yield func(string, func(p string, t *testing.T)
 	s.IterateBool("UniquePatterns", s.model.UniquePatterns(), yield, seed)
 	s.IterateBool("LinkInstrTrack", s.model.LinkInstrTrack(), yield, seed)
 	// Strings
-	s.IterateString("FilePath", s.model.FilePath().String(), yield, seed)
-	s.IterateString("InstrumentName", s.model.InstrumentName().String(), yield, seed)
-	s.IterateString("InstrumentComment", s.model.InstrumentComment().String(), yield, seed)
-	s.IterateString("UnitSearchText", s.model.UnitSearch().String(), yield, seed)
+	s.IterateString("FilePath", s.model.FilePath(), yield, seed)
+	s.IterateString("InstrumentName", s.model.InstrumentName(), yield, seed)
+	s.IterateString("InstrumentComment", s.model.InstrumentComment(), yield, seed)
+	s.IterateString("UnitSearchText", s.model.UnitSearch(), yield, seed)
 	// Actions
 	s.IterateAction("AddTrack", s.model.AddTrack(), yield, seed)
 	s.IterateAction("DeleteTrack", s.model.DeleteTrack(), yield, seed)
@@ -162,7 +162,7 @@ func (s *modelFuzzState) IterateBool(name string, b tracker.Bool, yield func(str
 
 func (s *modelFuzzState) IterateString(name string, str tracker.String, yield func(string, func(p string, t *testing.T)) bool, seed int) {
 	yield(name+".Set", func(p string, t *testing.T) {
-		str.Set(fmt.Sprintf("%d", seed))
+		str.SetValue(fmt.Sprintf("%d", seed))
 	})
 }
 
diff --git a/tracker/string.go b/tracker/string.go
index 34e5b0c..55a8b42 100644
--- a/tracker/string.go
+++ b/tracker/string.go
@@ -2,13 +2,12 @@ package tracker
 
 type (
 	String struct {
-		StringData
+		value StringValue
 	}
 
-	StringData interface {
+	StringValue interface {
 		Value() string
-		setValue(string)
-		change(kind string) func()
+		SetValue(string) bool
 	}
 
 	FilePath          Model
@@ -18,31 +17,39 @@ type (
 	UnitComment       Model
 )
 
-func (v String) Set(value string) {
-	if v.Value() != value {
-		defer v.change("Set")()
-		v.setValue(value)
+func MakeString(value StringValue) String {
+	return String{value: value}
+}
+
+func (v String) SetValue(value string) bool {
+	if v.value == nil || v.value.Value() == value {
+		return false
 	}
+	return v.value.SetValue(value)
+}
+
+func (v String) Value() string {
+	if v.value == nil {
+		return ""
+	}
+	return v.value.Value()
 }
 
 // Model methods
 
-func (m *Model) FilePath() *FilePath                   { return (*FilePath)(m) }
-func (m *Model) InstrumentName() *InstrumentName       { return (*InstrumentName)(m) }
-func (m *Model) InstrumentComment() *InstrumentComment { return (*InstrumentComment)(m) }
-func (m *Model) UnitSearch() *UnitSearch               { return (*UnitSearch)(m) }
-func (m *Model) UnitComment() *UnitComment             { return (*UnitComment)(m) }
+func (m *Model) FilePath() String          { return MakeString((*FilePath)(m)) }
+func (m *Model) InstrumentName() String    { return MakeString((*InstrumentName)(m)) }
+func (m *Model) InstrumentComment() String { return MakeString((*InstrumentComment)(m)) }
+func (m *Model) UnitSearch() String        { return MakeString((*UnitSearch)(m)) }
+func (m *Model) UnitComment() String       { return MakeString((*UnitComment)(m)) }
 
 // FilePathString
 
-func (v *FilePath) String() String            { return String{v} }
-func (v *FilePath) Value() string             { return v.d.FilePath }
-func (v *FilePath) setValue(value string)     { v.d.FilePath = value }
-func (v *FilePath) change(kind string) func() { return func() {} }
+func (v *FilePath) Value() string              { return v.d.FilePath }
+func (v *FilePath) SetValue(value string) bool { v.d.FilePath = value; return true }
 
 // UnitSearchString
 
-func (v *UnitSearch) String() String { return String{v} }
 func (v *UnitSearch) Value() string {
 	// return current unit type string if not searching
 	if !v.d.UnitSearching {
@@ -57,18 +64,14 @@ func (v *UnitSearch) Value() string {
 		return v.d.UnitSearchString
 	}
 }
-func (v *UnitSearch) setValue(value string) {
+func (v *UnitSearch) SetValue(value string) bool {
 	v.d.UnitSearchString = value
 	v.d.UnitSearching = true
+	return true
 }
-func (v *UnitSearch) change(kind string) func() { return func() {} }
 
 // InstrumentNameString
 
-func (v *InstrumentName) String() String {
-	return String{v}
-}
-
 func (v *InstrumentName) Value() string {
 	if v.d.InstrIndex < 0 || v.d.InstrIndex >= len(v.d.Song.Patch) {
 		return ""
@@ -76,23 +79,17 @@ func (v *InstrumentName) Value() string {
 	return v.d.Song.Patch[v.d.InstrIndex].Name
 }
 
-func (v *InstrumentName) setValue(value string) {
+func (v *InstrumentName) SetValue(value string) bool {
 	if v.d.InstrIndex < 0 || v.d.InstrIndex >= len(v.d.Song.Patch) {
-		return
+		return false
 	}
+	defer (*Model)(v).change("InstrumentNameString", PatchChange, MinorChange)()
 	v.d.Song.Patch[v.d.InstrIndex].Name = value
-}
-
-func (v *InstrumentName) change(kind string) func() {
-	return (*Model)(v).change("InstrumentNameString."+kind, PatchChange, MinorChange)
+	return true
 }
 
 // InstrumentComment
 
-func (v *InstrumentComment) String() String {
-	return String{v}
-}
-
 func (v *InstrumentComment) Value() string {
 	if v.d.InstrIndex < 0 || v.d.InstrIndex >= len(v.d.Song.Patch) {
 		return ""
@@ -100,20 +97,17 @@ func (v *InstrumentComment) Value() string {
 	return v.d.Song.Patch[v.d.InstrIndex].Comment
 }
 
-func (v *InstrumentComment) setValue(value string) {
+func (v *InstrumentComment) SetValue(value string) bool {
 	if v.d.InstrIndex < 0 || v.d.InstrIndex >= len(v.d.Song.Patch) {
-		return
+		return false
 	}
+	defer (*Model)(v).change("InstrumentComment", PatchChange, MinorChange)()
 	v.d.Song.Patch[v.d.InstrIndex].Comment = value
-}
-
-func (v *InstrumentComment) change(kind string) func() {
-	return (*Model)(v).change("InstrumentComment."+kind, PatchChange, MinorChange)
+	return true
 }
 
 // UnitComment
 
-func (v *UnitComment) String() String { return String{v} }
 func (v *UnitComment) Value() string {
 	if v.d.InstrIndex < 0 || v.d.InstrIndex >= len(v.d.Song.Patch) ||
 		v.d.UnitIndex < 0 || v.d.UnitIndex >= len(v.d.Song.Patch[v.d.InstrIndex].Units) {
@@ -122,14 +116,12 @@ func (v *UnitComment) Value() string {
 	return v.d.Song.Patch[v.d.InstrIndex].Units[v.d.UnitIndex].Comment
 }
 
-func (v *UnitComment) setValue(value string) {
+func (v *UnitComment) SetValue(value string) bool {
 	if v.d.InstrIndex < 0 || v.d.InstrIndex >= len(v.d.Song.Patch) ||
 		v.d.UnitIndex < 0 || v.d.UnitIndex >= len(v.d.Song.Patch[v.d.InstrIndex].Units) {
-		return
+		return false
 	}
+	defer (*Model)(v).change("UnitComment", PatchChange, MinorChange)()
 	v.d.Song.Patch[v.d.InstrIndex].Units[v.d.UnitIndex].Comment = value
-}
-
-func (v *UnitComment) change(kind string) func() {
-	return (*Model)(v).change("UnitComment."+kind, PatchChange, MinorChange)
+	return true
 }