Unity script to open the IMGUI debugger. Useful for editor UI debugging! Make sure you put it in an Editor/ folder in your project

IMGUIDebugger.cs

using UnityEditor;
using System;

public static class IMGUIDebugger {

	static Type type = Type.GetType( "UnityEditor.GUIViewDebuggerWindow,UnityEditor" );

	[MenuItem( "Window/IMGUI Debugger" )]
	public static void Open() => EditorWindow.GetWindow( type ).Show();
	
}