diff --git a/application.go b/application.go
index 151fec0..7b9dee0 100644
--- a/application.go
+++ b/application.go
@@ -45,7 +45,7 @@ func (application *Application) OnQuit (
 // OnPress registers an event handler to be called when a key or mouse button
 // is pressed.
 func (application *Application) OnPress (
-	onPress func (button Button),
+	onPress func (button Button, modifiers Modifiers),
 ) {
 	application.callbackManager.onPress = onPress
 }
diff --git a/backends/x/event.go b/backends/x/event.go
index 0508407..b2b55a4 100644
--- a/backends/x/event.go
+++ b/backends/x/event.go
@@ -91,7 +91,9 @@ func (backend *Backend) handleButtonPress (
 		backend.compressScrollSum(&sum)
 		backend.callbackManager.RunScroll(sum.x, sum.y)
 	} else {
-		backend.callbackManager.RunPress(stone.Button(buttonEvent.Detail + 127))
+		backend.callbackManager.RunPress (
+			stone.Button(buttonEvent.Detail + 127),
+			stone.Modifiers { })
 	}
 }
 
@@ -110,7 +112,15 @@ func (backend *Backend) handleKeyPress (
 ) {
 	keyEvent := *event.KeyPressEvent
 	button   := backend.keycodeToButton(keyEvent.Detail, keyEvent.State)
-	backend.callbackManager.RunPress(button)
+	backend.callbackManager.RunPress (button, stone.Modifiers {
+		// FIXME these may not be correct in all cases
+		Shift:   (keyEvent.State & xproto.ModMaskShift)   > 0,
+		Control: (keyEvent.State & xproto.ModMaskControl) > 0,
+		Alt:     (keyEvent.State & xproto.ModMask1)       > 0,
+		// Meta:    (keyEvent.State & xproto.??)       > 0,
+		Super:   (keyEvent.State & xproto.ModMask4)       > 0,
+		// Hyper:   (keyEvent.State & xproto.??)       > 0,
+	})
 }
 
 func (backend *Backend) handleKeyRelease (
diff --git a/backends/x/unicode.go b/backends/x/unicode.go
index 8d186b0..47c9d61 100644
--- a/backends/x/unicode.go
+++ b/backends/x/unicode.go
@@ -1,6 +1,6 @@
 package x
 
-import "fmt"
+// import "fmt"
 import "unicode"
 import "github.com/jezek/xgb/xproto"
 import "github.com/jezek/xgbutil/keybind"
@@ -138,7 +138,7 @@ func (backend *Backend) keycodeToButton (
 	var selectedKeysym xproto.Keysym
 	var selectedRune   rune
 
-	fmt.Printf("AAA\t%X\t%X\t%X\t%X\n", symbol1, symbol2, symbol3, symbol4)
+	// fmt.Printf("AAA\t%X\t%X\t%X\t%X\n", symbol1, symbol2, symbol3, symbol4)
 	
 	// big ol list in the middle
 	switch {
diff --git a/event.go b/event.go
index edbaf2c..5e5cb79 100644
--- a/event.go
+++ b/event.go
@@ -2,7 +2,7 @@ package stone
 
 type CallbackManager struct {
 	onQuit      func ()
-	onPress     func (button Button)
+	onPress     func (button Button, modifiers Modifiers)
 	onRelease   func (button Button)
 	onResize    func ()
 	onMouseMove func (x, y int)
@@ -15,9 +15,9 @@ func (manager *CallbackManager) RunQuit () {
 	manager.onQuit()
 }
 
-func (manager *CallbackManager) RunPress (button Button) {
+func (manager *CallbackManager) RunPress (button Button, modifiers Modifiers) {
 	if manager.onPress == nil { return }
-	manager.onPress(button)
+	manager.onPress(button, modifiers)
 }
 
 func (manager *CallbackManager) RunRelease (button Button) {
diff --git a/examples/draw/main.go b/examples/draw/main.go
index 3bab734..b4846b6 100644
--- a/examples/draw/main.go
+++ b/examples/draw/main.go
@@ -34,7 +34,7 @@ func main () {
 	if err != nil { panic(err) }
 }
 
-func onPress (button stone.Button) {
+func onPress (button stone.Button, modifiers stone.Modifiers) {
 	if button == stone.MouseButtonLeft {
 		mousePressed = true
 		application.SetRune(0, 0, '+')
diff --git a/examples/printbuttons/main.go b/examples/printbuttons/main.go
index fc2a779..88439f0 100644
--- a/examples/printbuttons/main.go
+++ b/examples/printbuttons/main.go
@@ -32,7 +32,7 @@ func main () {
 	if err != nil { panic(err) }
 }
 
-func onPress (button stone.Button) {
+func onPress (button stone.Button, modifiers stone.Modifiers) {
 	println("press", button)
 }
 
diff --git a/examples/type/main.go b/examples/type/main.go
index a8285c7..bbb1966 100644
--- a/examples/type/main.go
+++ b/examples/type/main.go
@@ -55,7 +55,7 @@ func drawCaret () {
 	application.SetColor(caretX, caretY, stone.ColorDim)
 }
 
-func onPress (button stone.Button) {
+func onPress (button stone.Button, modifiers stone.Modifiers) {
 	width, height := application.Size()
 	
 	if button == stone.KeyEnter {
diff --git a/input.go b/input.go
index 78adbe9..026a5d1 100644
--- a/input.go
+++ b/input.go
@@ -33,10 +33,10 @@ const (
 	KeyRightShift   Button = 21
 	KeyLeftControl  Button = 22
 	KeyRightControl Button = 23
-	KeyLeftMeta     Button = 24
-	KeyRightMeta    Button = 25
-	KeyLeftAlt      Button = 26
-	KeyRightAlt     Button = 27	
+	KeyLeftAlt      Button = 24
+	KeyRightAlt     Button = 25
+	KeyLeftMeta     Button = 26
+	KeyRightMeta    Button = 27	
 	KeyLeftSuper    Button = 28
 	KeyRightSuper   Button = 29
 	KeyLeftHyper    Button = 30
@@ -82,3 +82,16 @@ func (button Button) Printable () (printable bool) {
 	printable = unicode.IsPrint(rune(button))
 	return
 }
+
+// Modifiers lists what modifier keys are being pressed. This is used in
+// conjunction with a button code in a button press event. These should be used
+// instead of attempting to track the state of the modifier keys, because there
+// is no guarantee that one press event will be coupled with one release event.
+type Modifiers struct {
+	Shift   bool
+	Control bool
+	Alt     bool
+	Meta    bool
+	Super   bool
+	Hyper   bool
+}