Demo For Unity GUI

DemoUnityGUIFeature.cs

using UnityEditor;

public class DemoUnityGUIFeature
{
	//name to identify this feature also used in the tabs of DemoUnityWindow
	public string name = "F";

	public DemoUnityGUIFeature()
	{

	}
	public DemoUnityGUIFeature(string _name)
	{
		name = _name;
	}

	public void DrawGUI()
	{
		//method to show when this feature is selected
		EditorGUILayout.LabelField($"Im you feature with Name: {name}");
	}
}

DemoUnityGUIMonoBehaviour.cs

using UnityEngine;

//this is a monobehavior with all private variables with Unity Attributes, 
//System Attributes and Custom Attributes so we demostrate how to show everything i a custom editor
//without any extra code for the editor
public class DemoUnityGUIMonoBehaviour : MonoBehaviour
{
	[SerializeField]
	private string myString = "Hello World";
	[SerializeField]
	private bool groupEnabled;
	[SerializeField]
	private bool myBool = false;

	[Range(0,1)]
	[SerializeField]
	private float myFloat = 1.23f;

	[MinMaxRange(0f,10f)][SerializeField][Tooltip("Esto es una prueba")]
	private RangedFloat rangedFloat = new RangedFloat();
}

DemoUnityGUIMonoBehaviourEditor.cs

using UnityEditor;
using UnityEngine;

[CanEditMultipleObjects]
[CustomEditor(typeof(DemoUnityGUIMonoBehaviour))]
public class DemoUnityGUIMonoBehaviourEditor : Editor
{
	//cached properties that we are going to get
	SerializedProperty myString;
	SerializedProperty groupEnabled;
	SerializedProperty myBool;
	SerializedProperty myFloat;
	SerializedProperty rangedFloat;

	//Cacheamos todas las propiedas serializadas
	public void OnEnable()
	{
		SetUp();
	}
	// Setup the SerializedProperties.
	// si los nombres cambian esto peta
	//cacheamos las propiedades
	public void SetUp()
	{
		myString = serializedObject.FindProperty("myString");
		groupEnabled = serializedObject.FindProperty("groupEnabled");
		myBool = serializedObject.FindProperty("myBool");
		myFloat = serializedObject.FindProperty("myFloat");
		rangedFloat = serializedObject.FindProperty("rangedFloat");
	}

	public override void OnInspectorGUI()
	{
		//need to calls this at the start of the onInspectorGUI because READ THIS: https://docs.unity3d.com/ScriptReference/SerializedObject.html
		serializedObject.Update();

		myString.stringValue = EditorGUILayout.TextField("Text Field", myString.stringValue);

		groupEnabled.boolValue = EditorGUILayout.BeginToggleGroup("Optional Settings", groupEnabled.boolValue);

		myBool.boolValue = EditorGUILayout.Toggle("Toggle", myBool.boolValue);
		if (myBool.boolValue)
		{
			//THIS SHOWS ALL THE ATTRIBUTES WITH THE PROPERTY
			EditorGUILayout.PropertyField(myFloat);
			EditorGUILayout.PropertyField(rangedFloat);
		}

		EditorGUILayout.EndToggleGroup();

		//need to calls this at the end of the onInspectorGUI
		serializedObject.ApplyModifiedProperties();
	}

}

DemoUnityWindow.cs

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

public class DemoUnityWindow : EditorWindow
{
	//random MonoBehaviour that we pick up or create in the scene for demostration
	private DemoUnityGUIMonoBehaviour o = null;
	// if the monobehavior wasnt found create and delete after window closes
	private bool monobehaviourWasNull = false;
	//current selected tab
	private int selelectedTab = 0;

	//random class that has a DrawGUI method for encapsualting logic
	private List<DemoUnityGUIFeature> features = new List<DemoUnityGUIFeature>();
	//names of the tabs filled with the names of the llist above
	private List<string> featureNames = new List<string>();

	[MenuItem( "Window/My Window" )]
	public static void ShowWindow ( )
	{
		GetWindow<DemoUnityWindow>();
	}

	private void Awake()
	{
		o = FindObjectOfType<DemoUnityGUIMonoBehaviour>();
		if(o == null)
		{
			monobehaviourWasNull = true;

			GameObject a = new GameObject();
			o = a.AddComponent<DemoUnityGUIMonoBehaviour>();
		}
		//fill list used for the window GUI
		features.AddRange(new List<DemoUnityGUIFeature>
		{
			new DemoUnityGUIFeature("Scenes"),
			new DemoUnityGUIFeature("Visualization"),
			new DemoUnityGUIFeature("Creation")
		});
		features.ForEach(x => featureNames.Add(x.name));
	}

	private void OnGUI ( )
	{
		//showing a Label
		GUILayout.Label("Base Settings", EditorStyles.boldLabel);
		
		//Drawing Tabs with the names of the feature and selecting a tab
		selelectedTab = GUILayout.Toolbar(selelectedTab, featureNames.ToArray());

		//draw the selected tab under this toolbar
		if(selelectedTab >= 0 && selelectedTab < featureNames.Count)
		{
			features[selelectedTab].DrawGUI();
		}

		//draw the editor of the monobehaviour cached from scene also caches if it has a custom editor
		if (o != null)
		{
			//gets the editor for that Unity.Object and shows it
			Editor.CreateEditor(o).OnInspectorGUI();
		}
	}

	private void OnDestroy()
	{
		//deletes the monobehaviour if it was created fro demostration
		if (monobehaviourWasNull)
		{
			DestroyImmediate(o.gameObject);
			monobehaviourWasNull = false;
		}
	}

}