How can i control the Focus event margin?

On a Hololens2 project with MRTK2.7 and Unity2020, I try to catch the focus event with IMixedRealityFocusChangedHandler. However, the default margin is relatively big, so when the objects are close to each other, it does not work.

In detail:
The blue/green squares are areas i want to catch focus on. The red rectangles symbolize the catch area for the focus event. Because they overlap, it does not work.

Where can i control these margins? I've been looking around and googled for days, but can't find any settings for this. The "Pointer Extent" and "Max Gaze Collision Distance" in the MixedRealityToolkit seem to have no effect:

Code to catch the focus:

    public class MyGazeFocus : MonoBehaviour, IMixedRealityFocusChangedHandler
    {
        private bool hasFocus = false;
  
        // Update is called once per frame
        void Update()
        {
            if (hasFocus)
            {
                // Do something, e.g. change color from blue to green
            }
        }
   
        public void OnFocusChanged(FocusEventData eventData)
        {
            if (eventData.NewFocusedObject == gameObject)
            {
                hasFocus = true;
            } else
            {
                hasFocus = false;
            }
        }

        public void OnBeforeFocusChange(FocusEventData eventData)
        {
            // empty
        }
    }

Thanks for any help on this! It would be best, if I can set the margin per object, so that the default stays the same but is samller for these specific objects.