A Layout tool for Unity3D for scoped OnGUI() programming with no garbage production.

GUILayTools.cs

using System;
using UnityEngine;
using System.Collections.Generic;

//
// GUI layout tools (c) Yuri Tikhomirov at Cerevrum Inc.
//
// A useless* tool not to produce more garbage when using with Unity3D IMGUI.
//
//  * - cause anyway IMGUI produces garbage inside
//

//
// Usage:
//
//  class MB : MonoBehaviour {
//    GUILayTools layout = new GUILayTools();
//    void OnGUI() {
//      using (layout.VerticalScope()) {
//        using (layout.ScrollViewScope(ref scrollPos)) {
//          ...
//        }
//      }
//    }
//

public class GUILayTools : IDisposable
{
	enum ScopeType
	{
		Area,
		Vertical,
		Horizontal,
		Scrollview,
	}

	private Stack<ScopeType> stack = new Stack<ScopeType>(32);

	public IDisposable AreaScope(Rect rect)
	{
		GUILayout.BeginArea(rect);
		stack.Push(ScopeType.Area);
		return this;
	}

	public IDisposable VerticalScope()
	{
		GUILayout.BeginVertical();
		stack.Push(ScopeType.Vertical);
		return this;
	}

	public IDisposable HorizontalScope()
	{
		GUILayout.BeginHorizontal();
		stack.Push(ScopeType.Vertical);
		return this;
	}

	public IDisposable ScrollViewScope(ref Vector2 scrollPosition)
	{
		scrollPosition = GUILayout.BeginScrollView(scrollPosition);
		stack.Push(ScopeType.Scrollview);
		return this;
	}

	#region IDisposable implementation
	public void Dispose ()
	{
		var scope = stack.Pop();
		switch (scope)
		{
		case ScopeType.Area:
			GUILayout.EndArea();
			break;
		case ScopeType.Vertical:
			GUILayout.EndVertical();
			break;
		case ScopeType.Horizontal:
			GUILayout.EndHorizontal();
			break;
		case ScopeType.Scrollview:
			GUILayout.EndScrollView();
			break;
		}
	}
	#endregion
}