UnityEngine.GUILayout.Toolbar(int, UnityEngine.GUIContent[], UnityEngine.GUIStyle, UnityEngine.GUI.ToolbarButtonSize, params UnityEngine.GUILayoutOption[])

void ModeToggle()
        {
            GUILayout.BeginHorizontal();
            GUILayout.Space(k_ToolbarPadding);
            bool clicked = false;
            switch(m_Mode)
            {
                case Mode.Browser:
                    clicked = GUILayout.Button(m_RefreshTexture);
                    if (clicked)
                        m_ManageTab.ForceReloadData();
                    break;
                case Mode.Builder:
                    GUILayout.Space(m_RefreshTexture.width + k_ToolbarPadding);
                    break;
                case Mode.Inspect:
                    clicked = GUILayout.Button(m_RefreshTexture);
                    if (clicked)
                        m_InspectTab.RefreshBundles();
                    break;
            }

            float toolbarWidth = position.width - k_ToolbarPadding * 4 - m_RefreshTexture.width;
            //string[] labels = new string[2] { "Configure", "Build"};
            string[] labels = new string[3] { "Configure", "Build", "Inspect" };
            m_Mode = (Mode)GUILayout.Toolbar((int)m_Mode, labels, "LargeButton", GUILayout.Width(toolbarWidth) );
            GUILayout.FlexibleSpace();
            GUILayout.EndHorizontal();
            if(multiDataSource)
            {
                //GUILayout.BeginArea(r);
                GUILayout.BeginHorizontal();

                using (new EditorGUILayout.HorizontalScope(EditorStyles.toolbar))
                {
                    GUILayout.Label("Bundle Data Source:");
                    GUILayout.FlexibleSpace();
                    var c = new GUIContent(string.Format("{0} ({1})", replacedetBundleModel.Model.DataSource.Name, replacedetBundleModel.Model.DataSource.ProviderName), "Select replacedet Bundle Set");
                    if (GUILayout.Button(c , EditorStyles.toolbarPopup) )
                    {
                        GenericMenu menu = new GenericMenu();

                        for (int index = 0; index < m_DataSourceList.Count; index++)
                        {
                            var ds = m_DataSourceList[index];
                            if (ds == null)
                                continue;

                            if (index > 0)
                                menu.AddSeparator("");
                             
                            var counter = index;
                            menu.AddItem(new GUIContent(string.Format("{0} ({1})", ds.Name, ds.ProviderName)), false,
                                () =>
                                {
                                    m_DataSourceIndex = counter;
                                    var thisDataSource = ds;
                                    replacedetBundleModel.Model.DataSource = thisDataSource;
                                    m_ManageTab.ForceReloadData();
                                }
                            );

                        }

                        menu.ShowAsContext();
                    }

                    GUILayout.FlexibleSpace();
                    if (replacedetBundleModel.Model.DataSource.IsReadOnly())
                    {
                        GUIStyle tbLabel = new GUIStyle(EditorStyles.toolbar);
                        tbLabel.alignment = TextAnchor.MiddleRight;

                        GUILayout.Label("Read Only", tbLabel);
                    }
                }

                GUILayout.EndHorizontal();
                //GUILayout.EndArea();
            }
        }