Draw Gizmos and Handles in the scene from an EditorWindow

Is there any way to draw gizmos and handles in the scene from an editor window without adding an auxiliar GameObject to the scene?
I have tried

void OnGUI()
{
	Gizmos.DrawCube(Vector3.zero, new Vector3(1, 1, 1));
}

and

SceneView.onSceneGUIDelegate += window.OnSceneGUI

public void OnSceneGUI(SceneView scnView)
{
	Gizmos.DrawCube(Vector3.zero, new Vector3(1, 1, 1);
}

but both of course draw to the window instead of the scene.

After drawing all your handles, just call:

HandleUtility.Repaint();