Added Pos methods to DisplayDrag{Enter,Move}Event.

ui/event.go

@@ -12,6 +12,10 @@ type DisplayDragEnterEvent struct {
 	Files []string
 }
 
+func (e DisplayDragEnterEvent) Pos() geom.PointF32 {
+	return geom.PtF32(e.X, e.Y)
+}
+
 type DisplayDragLeaveEvent struct {
 	EventBase
 }
@@ -21,6 +25,10 @@ type DisplayDragMoveEnter struct {
 	X, Y float32
 }
 
+func (e DisplayDragMoveEnter) Pos() geom.PointF32 {
+	return geom.PtF32(e.X, e.Y)
+}
+
 type DisplayDropEvent struct {
 	EventBase
 	X, Y  float32