diff --git a/collision/label.go b/collision/label.go
index 44061986..633d41b3 100644
--- a/collision/label.go
+++ b/collision/label.go
@@ -3,7 +3,6 @@ package collision
 const (
 	// NilLabel is used internally for spaces that are otherwise not
 	// given labels.
-	// TODO V3: why is this exported
 	NilLabel Label = -1
 )
 
diff --git a/config.go b/config.go
index a6fb14fa..7233308f 100644
--- a/config.go
+++ b/config.go
@@ -164,8 +164,6 @@ func ReaderConfig(r io.Reader) ConfigOption {
 }
 
 func (c Config) overwriteFrom(c2 Config) Config {
-	// TODO: is this the right place for these configuration pieces?
-	// TODO: is there other configuration that should go here?
 	if c2.Assets.AudioPath != "" {
 		c.Assets.AudioPath = c2.Assets.AudioPath
 	}
diff --git a/dlog/default.go b/dlog/default.go
index b7d58c3d..84511614 100644
--- a/dlog/default.go
+++ b/dlog/default.go
@@ -43,8 +43,6 @@ func NewLogger() Logger {
 // containing the logged data separated by spaces,
 // prepended with file and line information.
 // It only includes logs which pass the current filters.
-// Todo: use io.Multiwriter to simplify the writing to
-// both logfiles and stdout
 func (l *logger) dLog(level Level, in ...interface{}) {
 	//(pc uintptr, file string, line int, ok bool)
 	_, f, line, ok := runtime.Caller(2)
diff --git a/event/bus.go b/event/bus.go
index 2d27284c..fd40d082 100644
--- a/event/bus.go
+++ b/event/bus.go
@@ -60,6 +60,11 @@ func NewBus(callerMap *CallerMap) *Bus {
 	}
 }
 
+// SetCallerMap updates a bus to use a specific set of callers.
+func (b *Bus) SetCallerMap(cm *CallerMap) {
+	b.callerMap = cm
+}
+
 // An Event is an event name and an associated caller id
 type Event struct {
 	Name     string
diff --git a/event/handler.go b/event/handler.go
index 70c31be3..89624e7e 100644
--- a/event/handler.go
+++ b/event/handler.go
@@ -14,8 +14,6 @@ var (
 // Handler represents the necessary exported functions from an event.Bus
 // for use in oak internally, and thus the functions that need to be replaced
 // by alternative event handlers.
-// TODO V3: consider breaking down the bus into smaller components
-// for easier composition for external handler implementations
 type Handler interface {
 	WaitForEvent(name string) <-chan interface{}
 	// <Handler>
@@ -42,6 +40,11 @@ type Handler interface {
 	UnbindBindable(UnbindOption)
 }
 
+// A CallerMapper has an internal caller map that can be set.
+type CallerMapper interface {
+	SetCallerMap(*CallerMap)
+}
+
 // UpdateLoop is expected to internally call Update()
 // or do something equivalent at the given frameRate,
 // sending signals to the sceneCh after each Update().
diff --git a/mouse/mouse.go b/mouse/mouse.go
index da12e54f..7fcd47c1 100644
--- a/mouse/mouse.go
+++ b/mouse/mouse.go
@@ -20,8 +20,6 @@ const (
 	ButtonNone       = mouse.ButtonNone
 )
 
-//TODO V3: should event names be strings?
-
 // GetEventName returns a string event name given some mobile/mouse information
 func GetEventName(d mouse.Direction, b mouse.Button) string {
 	switch d {
diff --git a/sceneLoop.go b/sceneLoop.go
index 42b3d9e1..e4a31e8c 100644
--- a/sceneLoop.go
+++ b/sceneLoop.go
@@ -130,6 +130,9 @@ func (w *Window) sceneLoop(first string, trackingInputs bool) {
 		} else {
 			w.CallerMap = event.NewCallerMap()
 		}
+		if cmr, ok := w.eventHandler.(event.CallerMapper); ok {
+			cmr.SetCallerMap(w.CallerMap)
+		}
 		w.DrawStack.Clear()
 		w.DrawStack.PreDraw()
 
diff --git a/viewport_test.go b/viewport_test.go
index 3bf26b4c..96a3d113 100644
--- a/viewport_test.go
+++ b/viewport_test.go
@@ -9,7 +9,7 @@ import (
 )
 
 func sleep() {
-	// TODO V3: test how far we can bring this down and get consistent results
+	// TODO: test how far we can bring this down and get consistent results
 	time.Sleep(300 * time.Millisecond)
 }