private void DrawSoundDatabaseDropZone(SoundDatabase soundDatabase)
        {
            GUILayout.Label(GUIContent.none, GUILayout.ExpandWidth(true), GUILayout.Height(0));
            Rect lastRect = GUILayoutUtility.GetLastRect();
            var  dropRect = new Rect(lastRect.x + DGUI.Properties.Space(), lastRect.y - 2, DGUI.Properties.DefaultFieldWidth * 5, DGUI.Properties.SingleLineHeight); //calculate rect

            bool containsMouse = dropRect.Contains(Event.current.mousePosition);

            if (containsMouse)
            {
                DGUI.Colors.SetNormalGUIColorAlpha();

                switch (Event.current.type)
                {
                case EventType.DragUpdated:
                    bool containsAudioClip = DragAndDrop.objectReferences.OfType <AudioClip>().Any();
                    DragAndDrop.visualMode = containsAudioClip ? DragAndDropVisualMode.Copy : DragAndDropVisualMode.Rejected;
                    Event.current.Use();
                    Repaint();
                    break;

                case EventType.DragPerform:
                    IEnumerable <AudioClip> audioClips = DragAndDrop.objectReferences.OfType <AudioClip>();
                    bool undoRecorded = false;
                    foreach (AudioClip audioClip in audioClips)
                    {
                        if (!undoRecorded)
                        {
                            DoozyUtils.UndoRecordObject(soundDatabase, UILabels.AddSounds);
                            undoRecorded = true;
                        }

                        SoundGroupData soundGroupData = soundDatabase.Add(audioClip.name, false, false);
                        soundGroupData.Sounds.Add(new AudioData(audioClip));
                        soundGroupData.SetDirty(false);
                        soundDatabase.SetDirty(false);
                        m_needsSave = true;
                    }

                    Event.current.Use();
                    Repaint();
                    break;
                }
            }

            DGUI.Doozy.DrawDropZone(dropRect, containsMouse);
            GUILayout.Space(dropRect.width);
        }