var sliderValue : float = 1.0;

function OnGUI() {
    // Wrap everything in the designated GUI Area
    GUILayout.BeginArea (Rect (0,0,200,60));
    // Begin the singular Horizontal Group
    GUILayout.BeginHorizontal();
    // Place a Button normally
    GUILayout.RepeatButton ("A button with\ntwo lines");
    // Place a space between the button and the vertical area
    // so it fits the whole area
    GUILayout.FlexibleSpace();
    // Arrange two more Controls vertically beside the Button
    GUILayout.BeginVertical();    
    GUILayout.Box("Value:" + Mathf.Round(sliderValue));
    sliderValue = GUILayout.HorizontalSlider (sliderValue, 0.0, 10);

    // End the Groups and Area
    GUILayout.EndVertical();
    GUILayout.EndHorizontal();
    GUILayout.EndArea();
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    public float sliderValue = 1.0F;
    void OnGUI() {
        GUILayout.BeginArea(new Rect(0, 0, 200, 60));
        GUILayout.BeginHorizontal();
        GUILayout.RepeatButton("A button with\ntwo lines");
        GUILayout.FlexibleSpace();
        GUILayout.BeginVertical();
        GUILayout.Box("Value:" + Mathf.Round(sliderValue));
        sliderValue = GUILayout.HorizontalSlider(sliderValue, 0.0F, 10);
        GUILayout.EndVertical();
        GUILayout.EndHorizontal();
        GUILayout.EndArea();
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    public sliderValue as single = 1.0F

    def OnGUI():
        GUILayout.BeginArea(Rect(0, 0, 200, 60))
        GUILayout.BeginHorizontal()
        GUILayout.RepeatButton('A button with\ntwo lines')
        GUILayout.FlexibleSpace()
        GUILayout.BeginVertical()
        GUILayout.Box(('Value:' + Mathf.Round(sliderValue)))
        sliderValue = GUILayout.HorizontalSlider(sliderValue, 0.0F, 10)
        GUILayout.EndVertical()
        GUILayout.EndHorizontal()
        GUILayout.EndArea()