PlayDisplayDialog.cs
using UnityEditor;
public class PlayDisplayDialog
{
[MenuItem("Custom Menu/Play")]
public static void Play()
{
bool playOutput = EditorUtility.DisplayDialog("Play", "Are you sure you want to enter play mode?", "Yes", "No");
if (playOutput)
EditorApplication.EnterPlaymode();
else
EditorUtility.DisplayDialog("Canceled", "You canceled the play mode.", "OK");
}
}