textareatextwin.cs

namespace Codefarts.Tests
{
    using UnityEditor;

    using UnityEngine;

    public class textareatextwin : EditorWindow
    {
        private string text = string.Empty;

        public void OnGUI()
        {
            var style = GUI.skin.textArea;

            // Calling GUILayout.TextField like this allows it to behave like a TextArea
            this.text = GUILayout.TextField(this.text, 10, GUI.skin.textField, GUILayout.ExpandWidth(true));

            // this line fails because the underlying code calls a hidden GUI.DoTextField method that accepts a miltiline argument
            // but the multiline argument is set to false which causes the GUI.TextArea to behave like a GUI.TextField
            // and you are not able to press the return key to start a new line       
            this.text = GUI.TextArea(new Rect(0, 40, 100, 100), this.text, 10, style);

            // not specifying a style works fine but in my case I needed only one text area to use a custom font (Courier New) with a limited 
            // number of characters.
            this.text = GUI.TextArea(new Rect(110, 40, 100, 100), this.text, 10);
        }

        /*
        // ===========GUI ============
        public static string TextArea(Rect position, string text, int maxLength, GUIStyle style)
        {
            GUIContent gUIContent = GUIContent.Temp(text);
            GUI.DoTextField(position, GUIUtility.GetControlID(FocusType.Keyboard, position), gUIContent, false, maxLength, style);
            return gUIContent.text;
        }

        private static string TextArea(Rect position, GUIContent content, int maxLength, GUIStyle style)
        {
            GUIContent gUIContent = GUIContent.Temp(content.text, content.image);
            GUI.DoTextField(position, GUIUtility.GetControlID(FocusType.Keyboard, position), gUIContent, false, maxLength, style);
            return gUIContent.text;
        }

            // ========= GUILayout ==============
        public static string TextField(string text, int maxLength, GUIStyle style, params GUILayoutOption[] options)
        {
            return GUILayout.DoTextField(text, maxLength, true, style, options);
        }
         */

        [MenuItem("Test/Test Text Area Style Window")]
        public static void Display()
        {
            GetWindow<textareatextwin>().Show();
        }  
    }
}