diff --git a/event_test.go b/event_test.go
index c9f2415..93ff4d8 100644
--- a/event_test.go
+++ b/event_test.go
@@ -35,11 +35,11 @@ func eventLoop(s Screen, evch chan Event) {
 
 func TestMouseEvents(t *testing.T) {
 
-	s, ss := mkTestScreen(t, "")
+	s := mkTestScreen(t, "")
 	defer s.Fini()
 
 	s.EnableMouse()
-	ss.InjectMouse(4, 9, Button1, ModCtrl)
+	s.InjectMouse(4, 9, Button1, ModCtrl)
 	evch := make(chan Event)
 	em := &EventMouse{}
 	done := false
@@ -71,11 +71,11 @@ func TestMouseEvents(t *testing.T) {
 
 func TestChannelMouseEvents(t *testing.T) {
 
-	s, ss := mkTestScreen(t, "")
+	s := mkTestScreen(t, "")
 	defer s.Fini()
 
 	s.EnableMouse()
-	ss.InjectMouse(4, 9, Button1, ModCtrl)
+	s.InjectMouse(4, 9, Button1, ModCtrl)
 	evch := make(chan Event)
 	quit := make(chan struct{})
 	em := new(EventMouse)
diff --git a/runes_test.go b/runes_test.go
index 36fc78f..88bca5d 100644
--- a/runes_test.go
+++ b/runes_test.go
@@ -19,7 +19,7 @@ import (
 )
 
 func TestCanDisplayUTF8(t *testing.T) {
-	s, _ := mkTestScreen(t, "UTF-8")
+	s := mkTestScreen(t, "UTF-8")
 	defer s.Fini()
 
 	if s.CharacterSet() != "UTF-8" {
@@ -39,7 +39,7 @@ func TestCanDisplayUTF8(t *testing.T) {
 	}
 }
 func TestCanDisplayASCII(t *testing.T) {
-	s, _ := mkTestScreen(t, "US-ASCII")
+	s := mkTestScreen(t, "US-ASCII")
 	defer s.Fini()
 
 	if s.CharacterSet() != "US-ASCII" {
@@ -60,7 +60,7 @@ func TestCanDisplayASCII(t *testing.T) {
 }
 
 func TestRuneFallbacks(t *testing.T) {
-	s, _ := mkTestScreen(t, "US-ASCII")
+	s := mkTestScreen(t, "US-ASCII")
 	defer s.Fini()
 	if s.CharacterSet() != "US-ASCII" {
 		t.Errorf("Wrong character set: %v", s.CharacterSet())
diff --git a/sim_test.go b/sim_test.go
index cf992bb..0c1949f 100644
--- a/sim_test.go
+++ b/sim_test.go
@@ -18,20 +18,20 @@ import (
 	"testing"
 )
 
-func mkTestScreen(t *testing.T, charset string) (Screen, SimulationScreen) {
-	s, ss := NewSimulationScreen(charset)
-	if s == nil || ss == nil {
+func mkTestScreen(t *testing.T, charset string) SimulationScreen {
+	s := NewSimulationScreen(charset)
+	if s == nil {
 		t.Fatalf("Failed to get simulation screen")
 	}
 	if e := s.Init(); e != nil {
 		t.Fatalf("Failed to initialize screen: %v", e)
 	}
-	return s, ss
+	return s
 }
 
 func TestInitScreen(t *testing.T) {
 
-	s, ss := mkTestScreen(t, "")
+	s := mkTestScreen(t, "")
 	defer s.Fini()
 
 	if x, y := s.Size(); x != 80 || y != 25 {
@@ -40,16 +40,16 @@ func TestInitScreen(t *testing.T) {
 	if s.CharacterSet() != "UTF-8" {
 		t.Fatalf("Character Set (%v) not UTF-8", s.CharacterSet())
 	}
-	if b, x, y := ss.GetContents(); len(b) != x*y || x != 80 || y != 25 {
+	if b, x, y := s.GetContents(); len(b) != x*y || x != 80 || y != 25 {
 		t.Fatalf("Contents (%v, %v, %v) wrong", len(b), x, y)
 	}
 }
 
 func TestClearScreen(t *testing.T) {
-	s, ss := mkTestScreen(t, "")
+	s := mkTestScreen(t, "")
 	defer s.Fini()
 	s.Clear()
-	b, x, y := ss.GetContents()
+	b, x, y := s.GetContents()
 	if len(b) != x*y || x != 80 || y != 25 {
 		t.Fatalf("Contents (%v, %v, %v) wrong", len(b), x, y)
 	}
@@ -65,10 +65,10 @@ func TestClearScreen(t *testing.T) {
 
 func TestSetCell(t *testing.T) {
 	st := StyleDefault.Background(ColorRed).Blink(true)
-	s, ss := mkTestScreen(t, "")
+	s := mkTestScreen(t, "")
 	defer s.Fini()
 	s.SetCell(2, 5, st, '@')
-	b, _, _ := ss.GetContents()
+	b, _, _ := s.GetContents()
 	s.Show()
 	if len(b) != 80*25 {
 		t.Fatalf("Wrong content size")
@@ -83,10 +83,10 @@ func TestSetCell(t *testing.T) {
 
 func TestResize(t *testing.T) {
 	st := StyleDefault.Background(ColorYellow).Underline(true)
-	s, ss := mkTestScreen(t, "")
+	s := mkTestScreen(t, "")
 	defer s.Fini()
 	s.SetCell(2, 5, st, '&')
-	b, x, y := ss.GetContents()
+	b, x, y := s.GetContents()
 	s.Show()
 
 	cell := &b[5*80+2]
@@ -97,7 +97,7 @@ func TestResize(t *testing.T) {
 	}
 	s.SetSize(30, 10)
 	s.Show()
-	b2, x2, y2 := ss.GetContents()
+	b2, x2, y2 := s.GetContents()
 	if len(b2) == len(b) || x2 == x || y2 == y {
 		t.Errorf("Screen parameters should not match")
 	}
@@ -111,17 +111,17 @@ func TestResize(t *testing.T) {
 }
 
 func TestBeep(t *testing.T) {
-	s, ss := mkTestScreen(t, "")
+	s := mkTestScreen(t, "")
 	defer s.Fini()
 
-	b0, x0, y0 := ss.GetContents()
+	b0, x0, y0 := s.GetContents()
 
 	if err := s.Beep(); err != nil {
 		t.Errorf("could not beep: %v", err)
 	}
 	s.Show()
 
-	b1, x1, y1 := ss.GetContents()
+	b1, x1, y1 := s.GetContents()
 	if x0 != x1 {
 		t.Fatalf("screen width changed unexpectedly from %d to %d", x0, x1)
 	}
diff --git a/simulation.go b/simulation.go
index 61814cf..ff6dae1 100644
--- a/simulation.go
+++ b/simulation.go
@@ -23,19 +23,21 @@ import (
 
 // NewSimulationScreen returns a SimulationScreen.  Note that
 // SimulationScreen is also a Screen.
-func NewSimulationScreen(charset string) (Screen, SimulationScreen) {
+func NewSimulationScreen(charset string) SimulationScreen {
 	if charset == "" {
 		charset = "UTF-8"
 	}
 	ss := &simscreen{charset: charset}
-	s := &baseScreen{screenImpl: ss}
-	return s, ss
+	ss.Screen = &baseScreen{screenImpl: ss}
+	return ss
 }
 
 // SimulationScreen represents a screen simulation.  This is intended to
 // be a superset of normal Screens, but also adds some important interfaces
 // for testing.
 type SimulationScreen interface {
+	Screen
+
 	// InjectKeyBytes injects a stream of bytes corresponding to
 	// the native encoding (see charset).  It turns true if the entire
 	// set of bytes were processed and delivered as KeyEvents, false
@@ -97,6 +99,7 @@ type simscreen struct {
 	fillstyle Style
 	fallback  map[rune]string
 
+	Screen
 	sync.Mutex
 }
 
diff --git a/style_test.go b/style_test.go
index 9d23b4c..861c65f 100644
--- a/style_test.go
+++ b/style_test.go
@@ -19,7 +19,7 @@ import (
 )
 
 func TestStyle(t *testing.T) {
-	s, _ := mkTestScreen(t, "")
+	s := mkTestScreen(t, "")
 	defer s.Fini()
 
 	style := StyleDefault