ObjectList.OnGUI C# (CSharp) Method

    void OnGUI()
    {
        //testing skins - amy
        GUI.skin = customSkin;

        GUILayout.BeginArea(bgRect, GUI.skin.window);
        scrollPosition = GUILayout.BeginScrollView(scrollPosition, false, false);
        GUILayout.BeginVertical (GUI.skin.box);

        customStyle = GUI.skin.button;

        selected = GUILayout.SelectionGrid(selected, listItems, 1, customStyle, GUILayout.ExpandWidth(true));

        if (selected >= 0) {
            objectSelected = listItems [selected];

            List<string> paramList = new List<string>();

            if (parameterList.availableParams.ContainsKey(objectSelected)) {
                paramList.AddRange(parameterList.availableParams[objectSelected]);
            }

            parameterList.listItems = paramList.ToArray();
        }

        GUILayout.EndVertical();
        GUILayout.EndScrollView();
        GUILayout.EndArea();

        Vector2 textDimensions = GUI.skin.label.CalcSize(new GUIContent("Objects"));

        GUI.Label (new Rect (((2*bgLeft+bgWidth)/2)-textDimensions.x/2, bgTop, textDimensions.x, 25), "Objects");

        GUI.enabled = (selected != -1);
        if (GUI.Button(new Rect(bgLeft, bgTop+bgHeight+Screen.height/48, bgWidth, 25),new GUIContent("Add"))){
            assetManager.InstantiateObject(objectSelected);

        }
        GUI.enabled = true;

        GUI.enabled = false;
        if (GUI.Button(new Rect(bgLeft, bgTop+bgHeight+(Screen.height/48)+30, bgWidth, 25),new GUIContent("Export Assets"))){
            assetManager.ExportAssets();

        }
        GUI.enabled = true;
    }