diff --git a/tracker/draglist.go b/tracker/draglist.go
index 3a71ad2..d93f5d4 100644
--- a/tracker/draglist.go
+++ b/tracker/draglist.go
@@ -61,7 +61,6 @@ func (s *FilledDragListStyle) Layout(gtx C) D {
 			s.dragList.tags = append(s.dragList.tags, false)
 		}
 		bg := func(gtx C) D {
-			gtx.Constraints = layout.Exact(image.Pt(120, 20))
 			var color color.NRGBA
 			if s.dragList.SelectedItem == index {
 				color = s.SelectedColor
diff --git a/tracker/instruments.go b/tracker/instruments.go
index 80bf95d..54f0eab 100644
--- a/tracker/instruments.go
+++ b/tracker/instruments.go
@@ -9,7 +9,6 @@ import (
 	"gioui.org/op/clip"
 	"gioui.org/op/paint"
 	"gioui.org/unit"
-	"gioui.org/widget"
 	"gioui.org/widget/material"
 	"golang.org/x/exp/shiny/materialdesign/icons"
 )
@@ -19,13 +18,13 @@ type D = layout.Dimensions
 
 func (t *Tracker) updateInstrumentScroll() {
 	if t.CurrentInstrument > 7 {
-		t.InstrumentList.Position.First = t.CurrentInstrument - 7
+		t.InstrumentDragList.List.Position.First = t.CurrentInstrument - 7
 	} else {
-		t.InstrumentList.Position.First = 0
+		t.InstrumentDragList.List.Position.First = 0
 	}
 }
 
-func (t *Tracker) layoutInstruments() layout.Widget {
+func (t *Tracker) layoutInstruments(gtx C) D {
 	btnStyle := material.IconButton(t.Theme, t.NewInstrumentBtn, widgetForIcon(icons.ContentAdd))
 	btnStyle.Background = transparent
 	btnStyle.Inset = layout.UniformInset(unit.Dp(6))
@@ -34,23 +33,21 @@ func (t *Tracker) layoutInstruments() layout.Widget {
 	} else {
 		btnStyle.Color = disabledTextColor
 	}
-	return func(gtx C) D {
-		return layout.Flex{Axis: layout.Vertical}.Layout(gtx,
-			layout.Rigid(func(gtx C) D {
-				return layout.Flex{}.Layout(
-					gtx,
-					layout.Flexed(1, t.layoutInstrumentNames()),
-					layout.Rigid(func(gtx C) D {
-						return layout.E.Layout(gtx, btnStyle.Layout)
-					}),
-				)
-			}),
-			layout.Rigid(t.layoutInstrumentHeader()),
-			layout.Flexed(1, t.layoutInstrumentEditor()))
-	}
+	return layout.Flex{Axis: layout.Vertical}.Layout(gtx,
+		layout.Rigid(func(gtx C) D {
+			return layout.Flex{}.Layout(
+				gtx,
+				layout.Flexed(1, t.layoutInstrumentNames),
+				layout.Rigid(func(gtx C) D {
+					return layout.E.Layout(gtx, btnStyle.Layout)
+				}),
+			)
+		}),
+		layout.Rigid(t.layoutInstrumentHeader),
+		layout.Flexed(1, t.layoutInstrumentEditor))
 }
 
-func (t *Tracker) layoutInstrumentHeader() layout.Widget {
+func (t *Tracker) layoutInstrumentHeader(gtx C) D {
 	headerBg := func(gtx C) D {
 		paint.FillShape(gtx.Ops, instrumentSurfaceColor, clip.Rect{
 			Max: gtx.Constraints.Min,
@@ -87,48 +84,35 @@ func (t *Tracker) layoutInstrumentHeader() layout.Widget {
 	for t.DeleteInstrumentBtn.Clicked() {
 		t.DeleteInstrument()
 	}
-	return func(gtx C) D {
-		return layout.Stack{Alignment: layout.Center}.Layout(gtx,
-			layout.Expanded(headerBg),
-			layout.Stacked(header))
-	}
+	return layout.Stack{Alignment: layout.Center}.Layout(gtx,
+		layout.Expanded(headerBg),
+		layout.Stacked(header))
 }
 
-func (t *Tracker) layoutInstrumentNames() layout.Widget {
-	return func(gtx C) D {
-		gtx.Constraints.Max.Y = gtx.Px(unit.Dp(36))
+func (t *Tracker) layoutInstrumentNames(gtx C) D {
+
+	element := func(gtx C, i int) D {
 		gtx.Constraints.Min.Y = gtx.Px(unit.Dp(36))
-
-		count := len(t.song.Patch.Instruments)
-		if len(t.InstrumentBtns) < count {
-			tail := make([]*widget.Clickable, count-len(t.InstrumentBtns))
-			for t := range tail {
-				tail[t] = new(widget.Clickable)
-			}
-			t.InstrumentBtns = append(t.InstrumentBtns, tail...)
-		}
-
-		defer op.Save(gtx.Ops).Load()
-
-		t.InstrumentList.Layout(gtx, count, func(gtx C, index int) D {
-			for t.InstrumentBtns[index].Clicked() {
-				t.CurrentInstrument = index
-			}
-			btnStyle := material.Button(t.Theme, t.InstrumentBtns[index], fmt.Sprintf("%v", index))
-			btnStyle.CornerRadius = unit.Dp(0)
-			btnStyle.Color = t.Theme.Fg
-			if t.CurrentInstrument == index {
-				btnStyle.Background = instrumentSurfaceColor
-			} else {
-				btnStyle.Background = transparent
-			}
-			return btnStyle.Layout(gtx)
+		labelStyle := LabelStyle{Text: fmt.Sprintf("%v", i), ShadeColor: black, Color: white, Font: labelDefaultFont, FontSize: unit.Sp(12)}
+		return layout.Inset{Left: unit.Dp(10), Right: unit.Dp(10)}.Layout(gtx, func(gtx C) D {
+			return layout.Center.Layout(gtx, labelStyle.Layout)
 		})
-
-		return layout.Dimensions{Size: gtx.Constraints.Max}
 	}
+
+	instrumentList := FilledDragList(t.Theme, t.InstrumentDragList, len(t.song.Patch.Instruments), element, t.SwapInstruments)
+	instrumentList.SelectedColor = instrumentSurfaceColor
+	instrumentList.HoverColor = instrumentHoverColor
+	instrumentList.SurfaceColor = transparent
+
+	t.InstrumentDragList.SelectedItem = t.CurrentInstrument
+	dims := instrumentList.Layout(gtx)
+	if t.CurrentInstrument != t.InstrumentDragList.SelectedItem {
+		t.CurrentInstrument = t.InstrumentDragList.SelectedItem
+		op.InvalidateOp{}.Add(gtx.Ops)
+	}
+	return dims
 }
-func (t *Tracker) layoutInstrumentEditor() layout.Widget {
+func (t *Tracker) layoutInstrumentEditor(gtx C) D {
 	for t.AddUnitBtn.Clicked() {
 		t.AddUnit()
 	}
@@ -149,23 +133,21 @@ func (t *Tracker) layoutInstrumentEditor() layout.Widget {
 
 	unitList := FilledDragList(t.Theme, t.UnitDragList, len(t.song.Patch.Instruments[t.CurrentInstrument].Units), element, t.SwapUnits)
 
-	return func(gtx C) D {
-		t.UnitDragList.SelectedItem = t.CurrentUnit
-		return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
-			layout.Rigid(func(gtx C) D {
-				return layout.Stack{Alignment: layout.SE}.Layout(gtx,
-					layout.Expanded(func(gtx C) D {
-						dims := unitList.Layout(gtx)
-						if t.CurrentUnit != t.UnitDragList.SelectedItem {
-							t.CurrentUnit = t.UnitDragList.SelectedItem
-							op.InvalidateOp{}.Add(gtx.Ops)
-						}
-						return dims
-					}),
-					layout.Stacked(func(gtx C) D {
-						return margin.Layout(gtx, addUnitBtnStyle.Layout)
-					}))
-			}),
-			layout.Rigid(t.layoutUnitEditor()))
-	}
+	t.UnitDragList.SelectedItem = t.CurrentUnit
+	return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
+		layout.Rigid(func(gtx C) D {
+			return layout.Stack{Alignment: layout.SE}.Layout(gtx,
+				layout.Expanded(func(gtx C) D {
+					dims := unitList.Layout(gtx)
+					if t.CurrentUnit != t.UnitDragList.SelectedItem {
+						t.CurrentUnit = t.UnitDragList.SelectedItem
+						op.InvalidateOp{}.Add(gtx.Ops)
+					}
+					return dims
+				}),
+				layout.Stacked(func(gtx C) D {
+					return margin.Layout(gtx, addUnitBtnStyle.Layout)
+				}))
+		}),
+		layout.Rigid(t.layoutUnitEditor))
 }
diff --git a/tracker/layout.go b/tracker/layout.go
index 0053aff..619159a 100644
--- a/tracker/layout.go
+++ b/tracker/layout.go
@@ -196,7 +196,7 @@ func (t *Tracker) layoutControls(gtx layout.Context) layout.Dimensions {
 
 	return t.TopHorizontalSplit.Layout(gtx,
 		t.layoutSongPanel,
-		t.layoutInstruments(),
+		t.layoutInstruments,
 	)
 
 }
diff --git a/tracker/theme.go b/tracker/theme.go
index d15abb7..d35a467 100644
--- a/tracker/theme.go
+++ b/tracker/theme.go
@@ -86,6 +86,7 @@ var patternSelectionColor = color.NRGBA{R: 19, G: 40, B: 60, A: 128}
 var inactiveBtnColor = color.NRGBA{R: 61, G: 55, B: 55, A: 255}
 
 var instrumentSurfaceColor = color.NRGBA{R: 45, G: 45, B: 45, A: 255}
+var instrumentHoverColor = color.NRGBA{R: 30, G: 31, B: 38, A: 255}
 
 var songSurfaceColor = color.NRGBA{R: 37, G: 37, B: 38, A: 255}
 
diff --git a/tracker/tracker.go b/tracker/tracker.go
index b57e0e6..59c7c73 100644
--- a/tracker/tracker.go
+++ b/tracker/tracker.go
@@ -53,9 +53,8 @@ type Tracker struct {
 	ClearUnitBtn          *widget.Clickable
 	ChooseUnitTypeList    *layout.List
 	ChooseUnitTypeBtns    []*widget.Clickable
-	InstrumentBtns        []*widget.Clickable
 	AddUnitBtn            *widget.Clickable
-	InstrumentList        *layout.List
+	InstrumentDragList    *DragList
 	TrackHexCheckBoxes    []*widget.Bool
 	TrackShowHex          []bool
 	TopHorizontalSplit    *Split
@@ -82,7 +81,7 @@ func (t *Tracker) LoadSong(song sointu.Song) error {
 	defer t.songPlayMutex.Unlock()
 	t.song = song
 	t.ClampPositions()
-	if l := len(t.song.Patch.Instruments); t.CurrentInstrument >= len(t.song.Patch.Instruments) {
+	if l := len(t.song.Patch.Instruments); t.CurrentInstrument >= l {
 		t.CurrentInstrument = l - 1
 	}
 	if l := len(t.song.Patch.Instruments[t.CurrentInstrument].Units); t.CurrentUnit >= l {
@@ -229,6 +228,16 @@ func (t *Tracker) AddInstrument() {
 	t.sequencer.SetPatch(t.song.Patch)
 }
 
+func (t *Tracker) SwapInstruments(i, j int) {
+	if i < 0 || j < 0 || i >= len(t.song.Patch.Instruments) || j >= len(t.song.Patch.Instruments) {
+		return
+	}
+	t.SaveUndo()
+	instruments := t.song.Patch.Instruments
+	instruments[i], instruments[j] = instruments[j], instruments[i]
+	t.sequencer.SetPatch(t.song.Patch)
+}
+
 func (t *Tracker) DeleteInstrument() {
 	if len(t.song.Patch.Instruments) <= 1 {
 		return
@@ -460,7 +469,7 @@ func New(audioContext sointu.AudioContext, synthService sointu.SynthService) *Tr
 		closer:                make(chan struct{}),
 		undoStack:             []sointu.Song{},
 		redoStack:             []sointu.Song{},
-		InstrumentList:        &layout.List{Axis: layout.Horizontal},
+		InstrumentDragList:    &DragList{List: &layout.List{Axis: layout.Horizontal}},
 		TopHorizontalSplit:    new(Split),
 		BottomHorizontalSplit: new(Split),
 		VerticalSplit:         new(Split),
diff --git a/tracker/uniteditor.go b/tracker/uniteditor.go
index 649ac95..d0c9ab5 100644
--- a/tracker/uniteditor.go
+++ b/tracker/uniteditor.go
@@ -15,59 +15,55 @@ import (
 	"golang.org/x/exp/shiny/materialdesign/icons"
 )
 
-func (t *Tracker) layoutUnitEditor() layout.Widget {
+func (t *Tracker) layoutUnitEditor(gtx C) D {
 	editorFunc := t.layoutUnitSliders
 	if t.song.Patch.Instruments[t.CurrentInstrument].Units[t.CurrentUnit].Type == "" {
 		editorFunc = t.layoutUnitTypeChooser
 	}
-	return func(gtx C) D {
-		paint.FillShape(gtx.Ops, unitSurfaceColor, clip.Rect{Max: image.Pt(gtx.Constraints.Max.X, gtx.Constraints.Max.Y)}.Op())
-		return layout.Flex{Axis: layout.Vertical}.Layout(gtx,
-			layout.Flexed(1, editorFunc()),
-			layout.Rigid(t.layoutUnitFooter()),
-		)
-	}
+	paint.FillShape(gtx.Ops, unitSurfaceColor, clip.Rect{Max: image.Pt(gtx.Constraints.Max.X, gtx.Constraints.Max.Y)}.Op())
+	return layout.Flex{Axis: layout.Vertical}.Layout(gtx,
+		layout.Flexed(1, editorFunc),
+		layout.Rigid(t.layoutUnitFooter()),
+	)
 }
 
-func (t *Tracker) layoutUnitSliders() layout.Widget {
-	return func(gtx C) D {
-		params := t.song.Patch.Instruments[t.CurrentInstrument].Units[t.CurrentUnit].Parameters
-		count := len(params)
-		children := make([]layout.FlexChild, 0, count)
-		if len(t.ParameterSliders) < count {
-			tail := make([]*widget.Float, count-len(t.ParameterSliders))
-			for t := range tail {
-				tail[t] = new(widget.Float)
-			}
-			t.ParameterSliders = append(t.ParameterSliders, tail...)
+func (t *Tracker) layoutUnitSliders(gtx C) D {
+	params := t.song.Patch.Instruments[t.CurrentInstrument].Units[t.CurrentUnit].Parameters
+	count := len(params)
+	children := make([]layout.FlexChild, 0, count)
+	if len(t.ParameterSliders) < count {
+		tail := make([]*widget.Float, count-len(t.ParameterSliders))
+		for t := range tail {
+			tail[t] = new(widget.Float)
 		}
-		keys := make([]string, 0, len(params))
-		for k := range params {
-			keys = append(keys, k)
-		}
-		sort.Strings(keys)
-		for i, k := range keys {
-			for t.ParameterSliders[i].Changed() {
-				params[k] = int(t.ParameterSliders[i].Value)
-				// TODO: tracker should have functions to update parameters and
-				// to do this efficiently i.e. not compile the whole patch again
-				t.LoadSong(t.song)
-			}
-			t.ParameterSliders[i].Value = float32(params[k])
-			sliderStyle := material.Slider(t.Theme, t.ParameterSliders[i], 0, 128)
-			sliderStyle.Color = t.Theme.Fg
-			k2 := k // avoid k changing in the closure
-			children = append(children, layout.Rigid(func(gtx C) D {
-				return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
-					layout.Rigid(Label(k2, white)),
-					layout.Rigid(func(gtx C) D {
-						gtx.Constraints.Min.X = 200
-						return sliderStyle.Layout(gtx)
-					}))
-			}))
-		}
-		return layout.Flex{Axis: layout.Vertical}.Layout(gtx, children...)
+		t.ParameterSliders = append(t.ParameterSliders, tail...)
 	}
+	keys := make([]string, 0, len(params))
+	for k := range params {
+		keys = append(keys, k)
+	}
+	sort.Strings(keys)
+	for i, k := range keys {
+		for t.ParameterSliders[i].Changed() {
+			params[k] = int(t.ParameterSliders[i].Value)
+			// TODO: tracker should have functions to update parameters and
+			// to do this efficiently i.e. not compile the whole patch again
+			t.LoadSong(t.song)
+		}
+		t.ParameterSliders[i].Value = float32(params[k])
+		sliderStyle := material.Slider(t.Theme, t.ParameterSliders[i], 0, 128)
+		sliderStyle.Color = t.Theme.Fg
+		k2 := k // avoid k changing in the closure
+		children = append(children, layout.Rigid(func(gtx C) D {
+			return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
+				layout.Rigid(Label(k2, white)),
+				layout.Rigid(func(gtx C) D {
+					gtx.Constraints.Min.X = 200
+					return sliderStyle.Layout(gtx)
+				}))
+		}))
+	}
+	return layout.Flex{Axis: layout.Vertical}.Layout(gtx, children...)
 }
 
 func (t *Tracker) layoutUnitFooter() layout.Widget {
@@ -104,28 +100,26 @@ func (t *Tracker) layoutUnitFooter() layout.Widget {
 	}
 }
 
-func (t *Tracker) layoutUnitTypeChooser() layout.Widget {
-	return func(gtx C) D {
-		paint.FillShape(gtx.Ops, unitSurfaceColor, clip.Rect{Max: image.Pt(gtx.Constraints.Max.X, gtx.Constraints.Max.Y)}.Op())
-		listElem := func(gtx C, i int) D {
-			for t.ChooseUnitTypeBtns[i].Clicked() {
-				t.SetUnit(allUnits[i])
-			}
-			labelStyle := LabelStyle{Text: allUnits[i], ShadeColor: black, Color: white, Font: labelDefaultFont, FontSize: unit.Sp(12)}
-			bg := func(gtx C) D {
-				gtx.Constraints = layout.Exact(image.Pt(120, 20))
-				var color color.NRGBA
-				if t.ChooseUnitTypeBtns[i].Hovered() {
-					color = unitTypeListHighlightColor
-				}
-				paint.FillShape(gtx.Ops, color, clip.Rect{Max: image.Pt(gtx.Constraints.Min.X, gtx.Constraints.Min.Y)}.Op())
-				return D{Size: gtx.Constraints.Min}
-			}
-			return layout.Stack{Alignment: layout.W}.Layout(gtx,
-				layout.Stacked(bg),
-				layout.Expanded(labelStyle.Layout),
-				layout.Expanded(t.ChooseUnitTypeBtns[i].Layout))
+func (t *Tracker) layoutUnitTypeChooser(gtx C) D {
+	paint.FillShape(gtx.Ops, unitSurfaceColor, clip.Rect{Max: image.Pt(gtx.Constraints.Max.X, gtx.Constraints.Max.Y)}.Op())
+	listElem := func(gtx C, i int) D {
+		for t.ChooseUnitTypeBtns[i].Clicked() {
+			t.SetUnit(allUnits[i])
 		}
-		return t.ChooseUnitTypeList.Layout(gtx, len(allUnits), listElem)
+		labelStyle := LabelStyle{Text: allUnits[i], ShadeColor: black, Color: white, Font: labelDefaultFont, FontSize: unit.Sp(12)}
+		bg := func(gtx C) D {
+			gtx.Constraints = layout.Exact(image.Pt(120, 20))
+			var color color.NRGBA
+			if t.ChooseUnitTypeBtns[i].Hovered() {
+				color = unitTypeListHighlightColor
+			}
+			paint.FillShape(gtx.Ops, color, clip.Rect{Max: image.Pt(gtx.Constraints.Min.X, gtx.Constraints.Min.Y)}.Op())
+			return D{Size: gtx.Constraints.Min}
+		}
+		return layout.Stack{Alignment: layout.W}.Layout(gtx,
+			layout.Stacked(bg),
+			layout.Expanded(labelStyle.Layout),
+			layout.Expanded(t.ChooseUnitTypeBtns[i].Layout))
 	}
+	return t.ChooseUnitTypeList.Layout(gtx, len(allUnits), listElem)
 }