diff --git a/artifact_card.go b/artifact_card.go
index 1bf76d4..87d84fe 100644
--- a/artifact_card.go
+++ b/artifact_card.go
@@ -10,15 +10,6 @@ import (
 	"mujicaui/theme"
 )
 
-// ArtifactKind is what an artifact holds; zero is ArtifactCode.
-type ArtifactKind int
-
-const (
-	ArtifactCode ArtifactKind = iota
-	ArtifactDocument
-	ArtifactWeb
-)
-
 // ArtifactCardOptions configure an ArtifactCard. Title is required.
 type ArtifactCardOptions struct {
 	Kind  ArtifactKind
diff --git a/command_block.go b/command_block.go
index 194e807..8d0c87f 100644
--- a/command_block.go
+++ b/command_block.go
@@ -12,17 +12,6 @@ import (
 	"mujicaui/theme"
 )
 
-// CommandRun is a command and its output from the caller.
-type CommandRun struct {
-	Command string
-	// Output may hold ANSI escapes.
-	Output   string
-	ExitCode int
-	Duration time.Duration
-	// Running hides ExitCode and Duration behind a live mark.
-	Running bool
-}
-
 // CommandBlockOptions configure a CommandBlock.
 type CommandBlockOptions struct {
 	// Prompt precedes the command; empty means "$".
diff --git a/internal/calendar.go b/internal/calendar.go
deleted file mode 100644
index 1b6164d..0000000
--- a/internal/calendar.go
+++ /dev/null
@@ -1,9 +0,0 @@
-package internal
-
-import "github.com/egoist/mygo/ui"
-
-// Rule draws a pixel-aligned 1 DIP horizontal line at y.
-func Rule(p *ui.Painter, x0, x1, y float32, c ui.Color) {
-	yy := ruleY(p, y)
-	p.Line(x0, yy, x1, yy, 1, c)
-}
diff --git a/internal/chart.go b/internal/chart.go
index 30286b9..47df0ea 100644
--- a/internal/chart.go
+++ b/internal/chart.go
@@ -189,12 +189,6 @@ func Sector(cx, cy, r0, r1 float32, a0, a1 float64) *ui.Path {
 	return &path
 }
 
-// Rule draws a pixel-aligned 1 DIP horizontal line at y.
-func Rule(p *ui.Painter, x0, x1, y float32, c ui.Color) {
-	yy := ruleY(p, y)
-	p.Line(x0, yy, x1, yy, 1, c)
-}
-
 // AxisY draws grid lines and tick labels left of plot.
 func AxisY(p *ui.Painter, plot ui.Rect, s Linear, ticks []float64, label func(float64) string, size float32, k theme.Tokens) {
 	for _, t := range ticks {
diff --git a/internal/display.go b/internal/display.go
index 3a00828..76a35ab 100644
--- a/internal/display.go
+++ b/internal/display.go
@@ -6,6 +6,12 @@ import (
 	"github.com/egoist/mygo/ui"
 )
 
+// Rule draws a pixel-aligned 1 DIP horizontal line at y.
+func Rule(p *ui.Painter, x0, x1, y float32, c ui.Color) {
+	yy := ruleY(p, y)
+	p.Line(x0, yy, x1, yy, 1, c)
+}
+
 // ruleY moves y to where a 1 DIP line fills whole device pixels.
 func ruleY(p *ui.Painter, y float32) float32 {
 	s := float64(p.Scale())
diff --git a/scatter_chart.go b/scatter_chart.go
index 99764f8..1703011 100644
--- a/scatter_chart.go
+++ b/scatter_chart.go
@@ -158,5 +158,3 @@ func ScatterChart(c *ui.Context, selected *[]ScatterKey, groups []ScatterGroup,
 func scatterRect(d scatterDrag, ox, oy float32) ui.Rect {
 	return ui.Rect{X: ox + min(d.x0, d.x1), Y: oy + min(d.y0, d.y1), W: abs32(d.x1 - d.x0), H: abs32(d.y1 - d.y0)}
 }
-
-func abs32(v float32) float32 { return max(v, -v) }