diff --git a/area.go b/area.go
index d6cbf3d..fbc629e 100644
--- a/area.go
+++ b/area.go
@@ -90,7 +90,7 @@ type MouseEvent struct {
 
 	// If the event was generated by a mouse button being released, Up contains the ID of that button.
 	// Otherwise, Up contains 0.
-	// If both Down and Up are 0, the event represents mouse movement (with optional held buttons; see below).
+	// If both Down and Up are 0, the event represents mouse movement (with optional held buttons for dragging; see below).
 	// Down and Up shall not both be nonzero.
 	Up			uint
 
@@ -106,6 +106,11 @@ type MouseEvent struct {
 	// Held will not include Down and Up.
 	// Held will be sorted.
 	// Only buttons 1, 2, and 3 are guaranteed to be detected by Held properly; whether or not any others are is implementation-defined.
+	// 
+	// If Held is non-empty but Up and Down are both zero, the mouse is being dragged, with all the buttons in Held being held.
+	// Whether or not a drag into an Area generates MouseEvents is implementation-defined.
+	// Whether or not a drag over an Area when the program is inactive generates MouseEvents is also implementation-defined.
+	// Moving the mouse over an Area when the program is inactive and no buttons are held will, however, generate MouseEvents.
 	Held			[]uint
 }
 
diff --git a/todo.md b/todo.md
index a248eff..69481f8 100644
--- a/todo.md
+++ b/todo.md
@@ -16,10 +16,7 @@ super ultra important things:
 - OS X: handle Insert/Help key change in a sane and deterministic way
 	- will need old and new Mac keyboards...
 - make sure MouseEvent's documentation has dragging described correctly (both Windows and GTK+ do)
-	- figure out what to do about dragging into or out of a window; will likely need to be undefined as well...
 - pin down whether or not a click event gets sent if this click changes from a different window to the one with the Area
-- determine if, on Mac OS X, dragging with two mouse buttons triggers both xxxMouseDragged: events
-- figure out what happens if the mouse button is held on another application, then dragged over an Area without activating that window
 - double-check to make sure MouseEvent.Held[] is sorted on all platforms
 - cap click count to 2 on all platforms
 - the windows build appears to be unstable: