Show a PopupWindow with negative margin on a MenuItem of the ActionBar

SomeActivity.java

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.menu_listoffers, menu);

    new Handler().post(new Runnable() {
        @Override
        public void run() {
            final View menuItemView = findViewById(R.id.action_search);

            View layoutOfPopup = getLayoutInflater().inflate(R.layout.popup_help_search, null);
            popupMessage = new PopupWindow(layoutOfPopup, ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
            popupMessage.setContentView(layoutOfPopup);
            popupMessage.showAsDropDown(menuItemView, -20, -20); //It's friday night, but you mustn't use magic numbers in real code!
        }
    });

    return super.onCreateOptionsMenu(menu);
}