fix(tracker/gioui): text.Shaper should not be a global variable

text.Shaper is not thread safe, which caused crash when adding
multiple VSTI plugins to a DAW project. This change fixes that
crash. Further refactorings need to consider where that text.Shaper
should actually reside.

CHANGELOG.md

@@ -18,6 +18,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
   options
 
 ### Fixed
+- Crash when running more than one sointu VSTI plugins in parallel
 - The scroll bars move in sync with the cursor.
 - The stereo version of delay in the go virtual machine (executables / plugins
   not ending with -native) applied the left delay taps on the right channel, and

tracker/gioui/alert.go

@@ -9,6 +9,7 @@ import (
 	"gioui.org/op"
 	"gioui.org/op/clip"
 	"gioui.org/op/paint"
+	"gioui.org/text"
 	"gioui.org/unit"
 )
 
@@ -22,6 +23,7 @@ type Alert struct {
 	showTime      time.Time
 	pos           float64
 	lastUpdate    time.Time
+	shaper        *text.Shaper
 }
 
 type AlertType int
@@ -94,7 +96,7 @@ func (a *Alert) Layout(gtx C) D {
 		}.Op())
 		return D{Size: gtx.Constraints.Min}
 	}
-	labelStyle := LabelStyle{Text: a.showMessage, Color: textColor, ShadeColor: shadeColor, Font: labelDefaultFont, Alignment: layout.Center, FontSize: unit.Sp(16)}
+	labelStyle := LabelStyle{Text: a.showMessage, Color: textColor, ShadeColor: shadeColor, Font: labelDefaultFont, Alignment: layout.Center, FontSize: unit.Sp(16), Shaper: a.shaper}
 	return alertMargin.Layout(gtx, func(gtx C) D {
 		return layout.S.Layout(gtx, func(gtx C) D {
 			defer op.Offset(image.Point{}).Push(gtx.Ops).Pop()

tracker/gioui/dialog.go

@@ -3,6 +3,7 @@ package gioui
 import (
 	"gioui.org/layout"
 	"gioui.org/op/paint"
+	"gioui.org/text"
 	"gioui.org/unit"
 	"gioui.org/widget"
 	"gioui.org/widget/material"
@@ -23,9 +24,10 @@ type DialogStyle struct {
 	AltStyle    material.ButtonStyle
 	OkStyle     material.ButtonStyle
 	CancelStyle material.ButtonStyle
+	Shaper      *text.Shaper
 }
 
-func ConfirmDialog(th *material.Theme, dialog *Dialog, text string) DialogStyle {
+func ConfirmDialog(th *material.Theme, dialog *Dialog, text string, shaper *text.Shaper) DialogStyle {
 	ret := DialogStyle{
 		dialog:      dialog,
 		Text:        text,
@@ -33,6 +35,7 @@ func ConfirmDialog(th *material.Theme, dialog *Dialog, text string) DialogStyle
 		AltStyle:    HighEmphasisButton(th, &dialog.BtnAlt, "Alt"),
 		OkStyle:     HighEmphasisButton(th, &dialog.BtnOk, "Ok"),
 		CancelStyle: HighEmphasisButton(th, &dialog.BtnCancel, "Cancel"),
+		Shaper:      shaper,
 	}
 	return ret
 }
@@ -44,7 +47,7 @@ func (d *DialogStyle) Layout(gtx C) D {
 			return Popup(&d.dialog.Visible).Layout(gtx, func(gtx C) D {
 				return d.Inset.Layout(gtx, func(gtx C) D {
 					return layout.Flex{Axis: layout.Vertical, Alignment: layout.Middle}.Layout(gtx,
-						layout.Rigid(Label(d.Text, highEmphasisTextColor)),
+						layout.Rigid(Label(d.Text, highEmphasisTextColor, d.Shaper)),
 						layout.Rigid(func(gtx C) D {
 							gtx.Constraints.Min.X = gtx.Dp(unit.Dp(120))
 							if d.ShowAlt {

tracker/gioui/instrumenteditor.go

@@ -155,7 +155,7 @@ func (ie *InstrumentEditor) Layout(gtx C, t *Tracker) D {
 					inset := layout.UniformInset(unit.Dp(6))
 					return inset.Layout(gtx, func(gtx C) D {
 						return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
-							layout.Rigid(Label("OCT:", white)),
+							layout.Rigid(Label("OCT:", white, t.TextShaper)),
 							layout.Rigid(octave),
 						)
 					})
@@ -193,7 +193,7 @@ func (ie *InstrumentEditor) layoutInstrumentHeader(gtx C, t *Tracker) D {
 		loadInstrumentBtnStyle := IconButton(t.Theme, ie.loadInstrumentBtn, icons.FileFolderOpen, true, "Load instrument")
 		deleteInstrumentBtnStyle := IconButton(t.Theme, ie.deleteInstrumentBtn, icons.ActionDelete, t.CanDeleteInstrument(), "Delete\ninstrument")
 
-		m := PopupMenu(t.Theme, &ie.presetMenu)
+		m := t.PopupMenu(&ie.presetMenu)
 
 		for item, clicked := ie.presetMenu.Clicked(); clicked; item, clicked = ie.presetMenu.Clicked() {
 			t.SetInstrument(tracker.InstrumentPresets[item])
@@ -201,7 +201,7 @@ func (ie *InstrumentEditor) layoutInstrumentHeader(gtx C, t *Tracker) D {
 
 		header := func(gtx C) D {
 			return layout.Flex{Axis: layout.Horizontal, Alignment: layout.Middle}.Layout(gtx,
-				layout.Rigid(Label("Voices: ", white)),
+				layout.Rigid(Label("Voices: ", white, t.TextShaper)),
 				layout.Rigid(func(gtx layout.Context) layout.Dimensions {
 					maxRemain := t.MaxInstrumentVoices()
 					t.InstrumentVoices.Value = t.Instrument().NumVoices
@@ -277,7 +277,7 @@ func (ie *InstrumentEditor) layoutInstrumentHeader(gtx C, t *Tracker) D {
 	}
 	for ie.deleteInstrumentBtn.Clickable.Clicked() {
 		if t.CanDeleteInstrument() {
-			dialogStyle := ConfirmDialog(t.Theme, ie.confirmInstrDelete, "Are you sure you want to delete this instrument?")
+			dialogStyle := ConfirmDialog(t.Theme, ie.confirmInstrDelete, "Are you sure you want to delete this instrument?", t.TextShaper)
 			ie.confirmInstrDelete.Visible = true
 			t.ModalDialog = dialogStyle.Layout
 		}
@@ -303,7 +303,7 @@ func (ie *InstrumentEditor) layoutInstrumentNames(gtx C, t *Tracker) D {
 	element := func(gtx C, i int) D {
 		gtx.Constraints.Min.Y = gtx.Dp(unit.Dp(36))
 		gtx.Constraints.Min.X = gtx.Dp(unit.Dp(30))
-		grabhandle := LabelStyle{Text: "", ShadeColor: black, Color: white, FontSize: unit.Sp(10), Alignment: layout.Center}
+		grabhandle := LabelStyle{Text: "", ShadeColor: black, Color: white, FontSize: unit.Sp(10), Alignment: layout.Center, Shaper: t.TextShaper}
 		if i == t.InstrIndex() {
 			grabhandle.Text = ":::"
 		}
@@ -346,7 +346,7 @@ func (ie *InstrumentEditor) layoutInstrumentNames(gtx C, t *Tracker) D {
 			if text == "" {
 				text = "Instr"
 			}
-			labelStyle := LabelStyle{Text: text, ShadeColor: black, Color: color, FontSize: unit.Sp(12)}
+			labelStyle := LabelStyle{Text: text, ShadeColor: black, Color: color, FontSize: unit.Sp(12), Shaper: t.TextShaper}
 			return layout.Center.Layout(gtx, labelStyle.Layout)
 		}
 		return layout.Inset{Left: unit.Dp(6), Right: unit.Dp(6)}.Layout(gtx, func(gtx C) D {
@@ -470,14 +470,14 @@ func (ie *InstrumentEditor) layoutInstrumentEditor(gtx C, t *Tracker) D {
 			editor.Font = labelDefaultFont
 			unitName = editor.Layout
 		} else {
-			unitNameLabel := LabelStyle{Text: u.Type, ShadeColor: black, Color: color, Font: labelDefaultFont, FontSize: unit.Sp(12)}
+			unitNameLabel := LabelStyle{Text: u.Type, ShadeColor: black, Color: color, Font: labelDefaultFont, FontSize: unit.Sp(12), Shaper: t.TextShaper}
 			if unitNameLabel.Text == "" {
 				unitNameLabel.Text = "---"
 			}
 			unitName = unitNameLabel.Layout
 		}
 
-		stackLabel := LabelStyle{Text: stackText, ShadeColor: black, Color: mediumEmphasisTextColor, Font: labelDefaultFont, FontSize: unit.Sp(12)}
+		stackLabel := LabelStyle{Text: stackText, ShadeColor: black, Color: mediumEmphasisTextColor, Font: labelDefaultFont, FontSize: unit.Sp(12), Shaper: t.TextShaper}
 		rightMargin := layout.Inset{Right: unit.Dp(10)}
 		return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
 			layout.Flexed(1, unitName),

tracker/gioui/label.go

@@ -20,6 +20,7 @@ type LabelStyle struct {
 	Alignment  layout.Direction
 	Font       font.Font
 	FontSize   unit.Sp
+	Shaper     *text.Shaper
 }
 
 func (l LabelStyle) Layout(gtx layout.Context) layout.Dimensions {
@@ -31,7 +32,7 @@ func (l LabelStyle) Layout(gtx layout.Context) layout.Dimensions {
 			dims := widget.Label{
 				Alignment: text.Start,
 				MaxLines:  1,
-			}.Layout(gtx, textShaper, l.Font, l.FontSize, l.Text, op.CallOp{})
+			}.Layout(gtx, l.Shaper, l.Font, l.FontSize, l.Text, op.CallOp{})
 			return layout.Dimensions{
 				Size:     dims.Size.Add(image.Pt(2, 2)),
 				Baseline: dims.Baseline,
@@ -42,11 +43,11 @@ func (l LabelStyle) Layout(gtx layout.Context) layout.Dimensions {
 			return widget.Label{
 				Alignment: text.Start,
 				MaxLines:  1,
-			}.Layout(gtx, textShaper, l.Font, l.FontSize, l.Text, op.CallOp{})
+			}.Layout(gtx, l.Shaper, l.Font, l.FontSize, l.Text, op.CallOp{})
 		}),
 	)
 }
 
-func Label(str string, color color.NRGBA) layout.Widget {
+func Label(str string, color color.NRGBA, shaper *text.Shaper) layout.Widget {
-	return LabelStyle{Text: str, Color: color, ShadeColor: black, Font: labelDefaultFont, FontSize: labelDefaultFontSize, Alignment: layout.W}.Layout
+	return LabelStyle{Text: str, Color: color, ShadeColor: black, Font: labelDefaultFont, FontSize: labelDefaultFontSize, Alignment: layout.W, Shaper: shaper}.Layout
 }

tracker/gioui/layout.go

@@ -38,7 +38,7 @@ func (t *Tracker) Layout(gtx layout.Context, w *app.Window) {
 			t.layoutBottom)
 	}
 	t.Alert.Layout(gtx)
-	dstyle := ConfirmDialog(t.Theme, t.ConfirmSongDialog, "Do you want to save your changes to the song? Your changes will be lost if you don't save them.")
+	dstyle := ConfirmDialog(t.Theme, t.ConfirmSongDialog, "Do you want to save your changes to the song? Your changes will be lost if you don't save them.", t.TextShaper)
 	dstyle.ShowAlt = true
 	dstyle.OkStyle.Text = "Save"
 	dstyle.AltStyle.Text = "Don't save"
@@ -56,7 +56,7 @@ func (t *Tracker) Layout(gtx layout.Context, w *app.Window) {
 	for t.ConfirmSongDialog.BtnCancel.Clicked() {
 		t.ConfirmSongDialog.Visible = false
 	}
-	dstyle = ConfirmDialog(t.Theme, t.WaveTypeDialog, "Export .wav in int16 or float32 sample format?")
+	dstyle = ConfirmDialog(t.Theme, t.WaveTypeDialog, "Export .wav in int16 or float32 sample format?", t.TextShaper)
 	dstyle.ShowAlt = true
 	dstyle.OkStyle.Text = "Int16"
 	dstyle.AltStyle.Text = "Float32"

tracker/gioui/menu.go

@@ -9,9 +9,9 @@ import (
 	"gioui.org/op"
 	"gioui.org/op/clip"
 	"gioui.org/op/paint"
+	"gioui.org/text"
 	"gioui.org/unit"
 	"gioui.org/widget"
-	"gioui.org/widget/material"
 )
 
 type Menu struct {
@@ -33,6 +33,7 @@ type MenuStyle struct {
 	FontSize      unit.Sp
 	IconSize      unit.Dp
 	HoverColor    color.NRGBA
+	Shaper        *text.Shaper
 }
 
 type MenuItem struct {
@@ -97,11 +98,11 @@ func (m *MenuStyle) Layout(gtx C, items ...MenuItem) D {
 						iconColor = mediumEmphasisTextColor
 					}
 					iconInset := layout.Inset{Left: unit.Dp(12), Right: unit.Dp(6)}
-					textLabel := LabelStyle{Text: item.Text, FontSize: m.FontSize, Color: m.TextColor}
+					textLabel := LabelStyle{Text: item.Text, FontSize: m.FontSize, Color: m.TextColor, Shaper: m.Shaper}
 					if item.Disabled {
 						textLabel.Color = mediumEmphasisTextColor
 					}
-					shortcutLabel := LabelStyle{Text: item.ShortcutText, FontSize: m.FontSize, Color: m.ShortCutColor}
+					shortcutLabel := LabelStyle{Text: item.ShortcutText, FontSize: m.FontSize, Color: m.ShortCutColor, Shaper: m.Shaper}
 					shortcutInset := layout.Inset{Left: unit.Dp(12), Right: unit.Dp(12), Bottom: unit.Dp(2), Top: unit.Dp(2)}
 					dims := layout.Flex{Axis: layout.Horizontal, Alignment: layout.Middle}.Layout(gtx,
 						layout.Rigid(func(gtx C) D {
@@ -147,7 +148,7 @@ func (m *MenuStyle) Layout(gtx C, items ...MenuItem) D {
 	return popup.Layout(gtx, contents)
 }
 
-func PopupMenu(th *material.Theme, menu *Menu) MenuStyle {
+func (t *Tracker) PopupMenu(menu *Menu) MenuStyle {
 	return MenuStyle{
 		Menu:          menu,
 		IconColor:     white,
@@ -156,5 +157,6 @@ func PopupMenu(th *material.Theme, menu *Menu) MenuStyle {
 		FontSize:      unit.Sp(16),
 		IconSize:      unit.Dp(16),
 		HoverColor:    menuHoverColor,
+		Shaper:        t.TextShaper,
 	}
 }

tracker/gioui/ordereditor.go

@@ -194,7 +194,7 @@ func (oe *OrderEditor) doLayout(gtx C, t *Tracker) D {
 			} else {
 				title = "?"
 			}
-			LabelStyle{Alignment: layout.N, Text: title, FontSize: unit.Sp(12), Color: mediumEmphasisTextColor}.Layout(gtx)
+			LabelStyle{Alignment: layout.N, Text: title, FontSize: unit.Sp(12), Color: mediumEmphasisTextColor, Shaper: t.TextShaper}.Layout(gtx)
 			return D{Size: gtx.Constraints.Min}
 		}
 		style := FilledDragList(t.Theme, oe.titleList, len(t.Song().Score.Tracks), elem, t.SwapTracks)
@@ -211,7 +211,7 @@ func (oe *OrderEditor) doLayout(gtx C, t *Tracker) D {
 			paint.FillShape(gtx.Ops, patternPlayColor, clip.Rect{Max: image.Pt(gtx.Constraints.Max.X, patternCellHeight)}.Op())
 		}
 		paint.ColorOp{Color: rowMarkerPatternTextColor}.Add(gtx.Ops)
-		widget.Label{}.Layout(gtx, textShaper, trackerFont, trackerFontSize, strings.ToUpper(fmt.Sprintf("%02x", j)), op.CallOp{})
+		widget.Label{}.Layout(gtx, t.TextShaper, trackerFont, trackerFontSize, strings.ToUpper(fmt.Sprintf("%02x", j)), op.CallOp{})
 		stack := op.Offset(image.Pt(patternRowMarkerWidth, 0)).Push(gtx.Ops)
 		for i, track := range t.Song().Score.Tracks {
 			paint.FillShape(gtx.Ops, patternCellColor, clip.Rect{Min: image.Pt(1, 1), Max: image.Pt(patternCellWidth-1, patternCellHeight-1)}.Op())
@@ -220,7 +220,7 @@ func (oe *OrderEditor) doLayout(gtx C, t *Tracker) D {
 				gtx := gtx
 				gtx.Constraints.Max.X = patternCellWidth
 				op.Offset(image.Pt(0, -2)).Add(gtx.Ops)
-				widget.Label{Alignment: text.Middle}.Layout(gtx, textShaper, trackerFont, trackerFontSize, patternIndexToString(track.Order[j]), op.CallOp{})
+				widget.Label{Alignment: text.Middle}.Layout(gtx, t.TextShaper, trackerFont, trackerFontSize, patternIndexToString(track.Order[j]), op.CallOp{})
 				op.Offset(image.Pt(0, 2)).Add(gtx.Ops)
 			}
 			point := tracker.ScorePoint{Track: i, ScoreRow: tracker.ScoreRow{Pattern: j}}

tracker/gioui/parameditor.go

@@ -199,7 +199,7 @@ func (pe *ParamEditor) layoutUnitFooter(t *Tracker) layout.Widget {
 		} else {
 			text = strings.Title(text)
 		}
-		hintText := Label(text, white)
+		hintText := Label(text, white, t.TextShaper)
 		return layout.Flex{Axis: layout.Horizontal, Alignment: layout.Middle}.Layout(gtx,
 			layout.Rigid(deleteUnitBtnStyle.Layout),
 			layout.Rigid(copyUnitBtnStyle.Layout),
@@ -226,7 +226,7 @@ func (pe *ParamEditor) layoutUnitTypeChooser(gtx C, t *Tracker) D {
 		if t.InstrumentEditor.unitTypeEditor.Focused() && !strings.HasPrefix(text, t.InstrumentEditor.unitTypeEditor.Text()) {
 			return D{}
 		}
-		labelStyle := LabelStyle{Text: text, ShadeColor: black, Color: white, Font: labelDefaultFont, FontSize: unit.Sp(12)}
+		labelStyle := LabelStyle{Text: text, ShadeColor: black, Color: white, Font: labelDefaultFont, FontSize: unit.Sp(12), Shaper: t.TextShaper}
 		bg := func(gtx C) D {
 			gtx.Constraints = layout.Exact(image.Pt(gtx.Constraints.Max.X, 20))
 			var color color.NRGBA

tracker/gioui/parameter.go

@@ -52,7 +52,7 @@ func (p ParameterStyle) Layout(gtx C) D {
 		layout.Rigid(func(gtx C) D {
 			return p.ParameterWidget.labelBtn.Layout(gtx, func(gtx C) D {
 				gtx.Constraints.Min.X = gtx.Dp(unit.Dp(110))
-				return layout.E.Layout(gtx, Label(p.Parameter.Name, white))
+				return layout.E.Layout(gtx, Label(p.Parameter.Name, white, p.tracker.TextShaper))
 			})
 		}),
 		layout.Rigid(func(gtx C) D {
@@ -154,7 +154,7 @@ func (p ParameterStyle) Layout(gtx C) D {
 		}),
 		layout.Rigid(func(gtx C) D {
 			if p.Parameter.Type != tracker.IDParameter {
-				return Label(p.Parameter.Hint, white)(gtx)
+				return Label(p.Parameter.Hint, white, p.tracker.TextShaper)(gtx)
 			}
 			return D{}
 		}),

tracker/gioui/rowmarkers.go

@@ -43,7 +43,7 @@ func (t *Tracker) layoutRowMarkers(gtx C) D {
 			}
 			if j == 0 {
 				paint.ColorOp{Color: rowMarkerPatternTextColor}.Add(gtx.Ops)
-				widget.Label{}.Layout(gtx, textShaper, trackerFont, trackerFontSize, strings.ToUpper(fmt.Sprintf("%02x", i)), op.CallOp{})
+				widget.Label{}.Layout(gtx, t.TextShaper, trackerFont, trackerFontSize, strings.ToUpper(fmt.Sprintf("%02x", i)), op.CallOp{})
 			}
 			if t.TrackEditor.Focused() && songRow == cursorSongRow {
 				paint.ColorOp{Color: trackerActiveTextColor}.Add(gtx.Ops)
@@ -51,7 +51,7 @@ func (t *Tracker) layoutRowMarkers(gtx C) D {
 				paint.ColorOp{Color: rowMarkerRowTextColor}.Add(gtx.Ops)
 			}
 			op.Offset(image.Pt(rowMarkerWidth/2, 0)).Add(gtx.Ops)
-			widget.Label{}.Layout(gtx, textShaper, trackerFont, trackerFontSize, strings.ToUpper(fmt.Sprintf("%02x", j)), op.CallOp{})
+			widget.Label{}.Layout(gtx, t.TextShaper, trackerFont, trackerFontSize, strings.ToUpper(fmt.Sprintf("%02x", j)), op.CallOp{})
 			op.Offset(image.Pt(-rowMarkerWidth/2, trackRowHeight)).Add(gtx.Ops)
 		}
 	}

tracker/gioui/songpanel.go

@@ -44,7 +44,7 @@ func (t *Tracker) layoutMenu(title string, clickable *widget.Clickable, menu *Me
 	for clickable.Clicked() {
 		menu.Visible = true
 	}
-	m := PopupMenu(t.Theme, menu)
+	m := t.PopupMenu(menu)
 	return func(gtx C) D {
 		defer op.Offset(image.Point{}).Push(gtx.Ops).Pop()
 		titleBtn := material.Button(t.Theme, clickable, title)
@@ -145,7 +145,7 @@ func (t *Tracker) layoutSongOptions(gtx C) D {
 	return layout.Flex{Axis: layout.Vertical}.Layout(gtx,
 		layout.Rigid(func(gtx C) D {
 			return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
-				layout.Rigid(Label("LEN:", white)),
+				layout.Rigid(Label("LEN:", white, t.TextShaper)),
 				layout.Rigid(func(gtx layout.Context) layout.Dimensions {
 					t.SongLength.Value = t.Song().Score.Length
 					numStyle := NumericUpDown(t.Theme, t.SongLength, 1, math.MaxInt32, "Song length")
@@ -159,7 +159,7 @@ func (t *Tracker) layoutSongOptions(gtx C) D {
 		}),
 		layout.Rigid(func(gtx C) D {
 			return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
-				layout.Rigid(Label("BPM:", white)),
+				layout.Rigid(Label("BPM:", white, t.TextShaper)),
 				layout.Rigid(func(gtx layout.Context) layout.Dimensions {
 					t.BPM.Value = t.Song().BPM
 					numStyle := NumericUpDown(t.Theme, t.BPM, 1, 999, "Beats per minute")
@@ -173,7 +173,7 @@ func (t *Tracker) layoutSongOptions(gtx C) D {
 		}),
 		layout.Rigid(func(gtx C) D {
 			return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
-				layout.Rigid(Label("RPP:", white)),
+				layout.Rigid(Label("RPP:", white, t.TextShaper)),
 				layout.Rigid(func(gtx layout.Context) layout.Dimensions {
 					t.RowsPerPattern.Value = t.Song().Score.RowsPerPattern
 					numStyle := NumericUpDown(t.Theme, t.RowsPerPattern, 1, 255, "Rows per pattern")
@@ -187,7 +187,7 @@ func (t *Tracker) layoutSongOptions(gtx C) D {
 		}),
 		layout.Rigid(func(gtx C) D {
 			return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
-				layout.Rigid(Label("RPB:", white)),
+				layout.Rigid(Label("RPB:", white, t.TextShaper)),
 				layout.Rigid(func(gtx layout.Context) layout.Dimensions {
 					t.RowsPerBeat.Value = t.Song().RowsPerBeat
 					numStyle := NumericUpDown(t.Theme, t.RowsPerBeat, 1, 32, "Rows per beat")
@@ -201,7 +201,7 @@ func (t *Tracker) layoutSongOptions(gtx C) D {
 		}),
 		layout.Rigid(func(gtx C) D {
 			return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
-				layout.Rigid(Label("STP:", white)),
+				layout.Rigid(Label("STP:", white, t.TextShaper)),
 				layout.Rigid(func(gtx layout.Context) layout.Dimensions {
 					numStyle := NumericUpDown(t.Theme, t.Step, 0, 8, "Cursor step")
 					numStyle.UnitsPerStep = unit.Dp(20)

tracker/gioui/theme.go

@@ -9,7 +9,6 @@ import (
 )
 
 var fontCollection []text.FontFace = gofont.Collection()
-var textShaper = text.NewShaper(text.WithCollection(fontCollection))
 
 var white = color.NRGBA{R: 255, G: 255, B: 255, A: 255}
 var black = color.NRGBA{R: 0, G: 0, B: 0, A: 255}

tracker/gioui/trackeditor.go

@@ -253,7 +253,7 @@ func (te *TrackEditor) Layout(gtx layout.Context, t *Tracker) layout.Dimensions
 			layout.Rigid(subtractOctaveBtnStyle.Layout),
 			layout.Rigid(noteOffBtnStyle.Layout),
 			layout.Rigid(hexCheckBoxStyle.Layout),
-			layout.Rigid(Label("  Voices:", white)),
+			layout.Rigid(Label("  Voices:", white, t.TextShaper)),
 			layout.Rigid(voiceUpDown),
 			layout.Flexed(1, func(gtx C) D { return layout.Dimensions{Size: gtx.Constraints.Min} }),
 			layout.Rigid(deleteTrackBtnStyle.Layout),
@@ -388,7 +388,7 @@ func (te *TrackEditor) layoutTracks(gtx C, t *Tracker) D {
 			}
 		}
 		gtx.Constraints.Max.X = trackColWidth
-		LabelStyle{Alignment: layout.N, Text: instrName, FontSize: unit.Sp(12), Color: mediumEmphasisTextColor}.Layout(gtx)
+		LabelStyle{Alignment: layout.N, Text: instrName, FontSize: unit.Sp(12), Color: mediumEmphasisTextColor, Shaper: t.TextShaper}.Layout(gtx)
 		op.Offset(image.Point{trackColWidth, 0}).Add(gtx.Ops)
 		curVoice += trk.NumVoices
 	}
@@ -461,11 +461,11 @@ func (te *TrackEditor) layoutTracks(gtx C, t *Tracker) D {
 			}
 			if s >= 0 && patRow == 0 {
 				paint.ColorOp{Color: trackerPatMarker}.Add(gtx.Ops)
-				widget.Label{}.Layout(gtx, textShaper, trackerFont, trackerFontSize, patternIndexToString(s), op.CallOp{})
+				widget.Label{}.Layout(gtx, t.TextShaper, trackerFont, trackerFontSize, patternIndexToString(s), op.CallOp{})
 			}
 			if s >= 0 && patRow == 1 && t.IsPatternUnique(trkIndex, s) {
 				paint.ColorOp{Color: mediumEmphasisTextColor}.Add(gtx.Ops)
-				widget.Label{}.Layout(gtx, textShaper, trackerFont, trackerFontSize, "*", op.CallOp{})
+				widget.Label{}.Layout(gtx, t.TextShaper, trackerFont, trackerFontSize, "*", op.CallOp{})
 			}
 			op.Offset(image.Point{patmarkWidth, 0}).Add(gtx.Ops)
 			if te.Focused() && t.Cursor().Row == patRow && t.Cursor().Pattern == pat {
@@ -487,9 +487,9 @@ func (te *TrackEditor) layoutTracks(gtx C, t *Tracker) D {
 				default:
 					text = fmt.Sprintf("%02x", c)
 				}
-				widget.Label{}.Layout(gtx, textShaper, trackerFont, trackerFontSize, strings.ToUpper(text), op.CallOp{})
+				widget.Label{}.Layout(gtx, t.TextShaper, trackerFont, trackerFontSize, strings.ToUpper(text), op.CallOp{})
 			} else {
-				widget.Label{}.Layout(gtx, textShaper, trackerFont, trackerFontSize, noteStr(c), op.CallOp{})
+				widget.Label{}.Layout(gtx, t.TextShaper, trackerFont, trackerFontSize, noteStr(c), op.CallOp{})
 			}
 			op.Offset(image.Point{-patmarkWidth, trackRowHeight}).Add(gtx.Ops)
 		}

tracker/gioui/tracker.go

@@ -11,6 +11,7 @@ import (
 	"gioui.org/io/system"
 	"gioui.org/layout"
 	"gioui.org/op"
+	"gioui.org/text"
 	"gioui.org/unit"
 	"gioui.org/widget"
 	"gioui.org/widget/material"
@@ -55,6 +56,8 @@ type Tracker struct {
 	TrackEditor           *TrackEditor
 	Explorer              *explorer.Explorer
 
+	TextShaper *text.Shaper
+
 	lastAvgVolume  tracker.Volume
 	lastPeakVolume tracker.Volume
 
@@ -153,6 +156,8 @@ func NewTracker(model *tracker.Model, synther sointu.Synther) *Tracker {
 		marshalRecoveryChannel:   make(chan (chan []byte)),
 		unmarshalRecoveryChannel: make(chan []byte),
 	}
+	t.TextShaper = text.NewShaper(text.WithCollection(fontCollection))
+	t.Alert.shaper = t.TextShaper
 	t.Theme.Palette.Fg = primaryColor
 	t.Theme.Palette.ContrastFg = black
 	t.TrackEditor.Focus()