Editor Window Views

Hi all. I have one problem:

I want to build one Editor Window with many views which will be swich by some state or "page number".

In one script it is wery easy:

 using UnityEditor;
 
 public class LessonWindow : EditorWindow {    
     
     public string State { get; set; }
     
     [MenuItem("Window/LessonWindow")]
     public static void ShowWindow(){
         EditorWindow.GetWindow(typeof(LessonWindow));
     }
 
     void OnGUI(){
         OnDrawContent();
     }
 
     public virtual void OnDrawContent() {
         switch (State) {
             case "State1":
                     GUILayout.Label ("Hello World 1");
             break;
             case "State2":
                     GUILayout.Label ("Hello World 2");
             break;
         }
     } 
 }

However I want to pack the logic in DLL (one Editor Window). And take out OnDrawContent() as resource in other script. Like creating much content for one renderer.