Version: 2017.3
public static GUILayoutOption ExpandWidth (bool expand);


Option passed to a control to allow or disallow horizontal expansion.

If this is true, the enclosed UI elements can expand to fill the available horizontal width.


using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour { void OnGUI() { GUILayout.BeginVertical(); GUILayout.Button("Short Button", GUILayout.ExpandWidth(false)); GUILayout.Button("Very very long Button"); GUILayout.EndVertical(); } }