gistfile1.txt

using UnityEngine;
using UnityEditor;

public class EditorWindowTest : EditorWindow 
{
	public string message; // messageスタティックやめるってよ	

	[MenuItem("Window/Show")]
	static void Init()
	{
		var window = EditorWindow.CreateInstance<EditorWindowTest> ();
		window.message = "C";
		window.Show ();
	}
	 
	void OnGUI()
	{
		GUILayout.Label (message);
		if (GUILayout.Button ("PUSH")) { message += "#"; }
	}
}