RelativeLayout/customview не заполняет ширину табуляции

Я пытаюсь заполнить вкладку с представлением. Для получения дополнительной информации о точной вещи, которую я пытаюсь достичь с учетом, прочитайте мой предыдущий вопрос: Как настроить отдельные вкладки? (изменение цвета фона, цвета индикатора и цвета текста)

В результате я получил следующее:

Как вы видите, вкладка не полностью заполнена представлением по ширине.

мой макет xml:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  

    android:layout_width="match_parent"
    android:layout_height="match_parent" 
    android:orientation="vertical"
    android:background ="@color/black" 
    >

  <TextView
      android:id="@+id/nieuws_tab_layout"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:gravity="center"
      android:text="@string/nieuws"
      android:textColor="@android:color/white"
      android:textStyle="bold"/>
</RelativeLayout>

My MainActivity:

package com.example.android.effectivenavigation;

import android.app.ActionBar;
import android.app.ActionBar.Tab;
import android.app.FragmentTransaction;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

public class MainActivity extends FragmentActivity implements ActionBar.TabListener
{
    AppSectionsPagerAdapter mAppSectionsPagerAdapter;
    //The viewpager displays on of the section at a time
    ViewPager mViewPager;

    public void onCreate(Bundle savedInstanceState)
    {       
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Create the adapter that will return a fragment for each of the three primary sections
        // of the app.
        mAppSectionsPagerAdapter = new AppSectionsPagerAdapter(getSupportFragmentManager());

        // Set up the action bar.
        final ActionBar actionBar = getActionBar();
        //set custom actionbar
        actionBar.setCustomView(R.layout.titlebar);
        //Displays the custom design in the actionbar
        actionBar.setDisplayShowCustomEnabled(true);
        //Turns the homeIcon a View     
        View homeIcon = findViewById(android.R.id.home);
        //Hides the View (and so the icon)
        ((View)homeIcon.getParent()).setVisibility(View.GONE);          

        // Specify that we will be displaying tabs in the action bar.
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

        // Set up the ViewPager, attaching the adapter and setting up a listener for when the
        // user swipes between sections.
        mViewPager = (ViewPager) findViewById(R.id.pager);
        mViewPager.setAdapter(mAppSectionsPagerAdapter);

        mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener()
        {           
            @Override
            public void onPageSelected(int position)
            {
                    // When swiping between different app sections, select the corresponding tab.
                    // We can also use ActionBar.Tab#select() to do this if we have a reference to the Tab.
                    actionBar.setSelectedNavigationItem(position);
            }
        });


        // For each of the sections in the app, add a tab to the action bar.
        for (int i = 0; i < mAppSectionsPagerAdapter.getCount(); i++)
        {
            if(i == 0)
            {
                //final View firstCustomView = new CustomView(this);
                //firstCustomView.setBackgroundColor(Color.BLUE);
                Tab tab = actionBar.newTab().setTabListener(this).setCustomView(R.layout.nieuws_tab_layout);

                actionBar.addTab(tab);
            }
            else
            {
            // Create a tab with text corresponding to the page title defined by the adapter.
            // Also specify this Activity object, which implements the TabListener interface, as the
            // listener for when this tab is selected.
            Tab tab = actionBar.newTab().setText(mAppSectionsPagerAdapter.getPageTitle(i)).setTabListener(this);            
            actionBar.addTab(tab);
            }
        }
    }

    @Override
    public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) 
    {
    }

    @Override
    public void onTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) 
    {
        //CustomView ctv;
        //ctv = new CustomView(context, R.attr.tabStyleAttr);
        // When the given tab is selected, switch to the corresponding page in the ViewPager.
        //LayoutInflater inflater = (LayoutInflater) getSystemService(LAYOUT_INFLATER_SERVICE);
        //View tabView = inflater.inflate(R.layout.nieuws_tab_layout, null);
        //tabView.setBackgroundColor(0xFF00FF00);
        //tab.setCustomView(tabView);  
        mViewPager.setCurrentItem(tab.getPosition());
    }

    @Override
    public void onTabReselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction)
    {
    }

    public static class AppSectionsPagerAdapter extends FragmentPagerAdapter 
    {
        public AppSectionsPagerAdapter(FragmentManager fm)
        {
            super(fm);
        }

        @Override
        public Fragment getItem(int i) 
        {
            switch (i)
            {
                case 0:
                    // The first section of the app is the most interesting -- it offers
                    // a launchpad into the other demonstrations in this example application.
                    return new LaunchpadSectionFragment();

                default:
                    // The other sections of the app are dummy placeholders.
                    Fragment fragment = new DummySectionFragment();
                    Bundle args = new Bundle();
                    args.putInt(DummySectionFragment.ARG_SECTION_NUMBER, i + 1);
                    fragment.setArguments(args);
                    return fragment;
            }
        }

        @Override
        public int getCount()
        {
            return 3;
        }

        @Override
        public CharSequence getPageTitle(int position) 
        {
            switch(position)
            {
                case 0:
                {
                    return "Tab1";
                }
                case 1:
                {
                    return "Tab2";
                }
                case 2:
                {
                    return "Tab3";
                }
                default:
                {
                    return "Section " + (position + 1);
                }
            }
        }
    }
    public static class LaunchpadSectionFragment extends Fragment
    {
        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState)
        {
            View rootView = inflater.inflate(R.layout.fragment_section_launchpad, container, false);

            // Demonstration of a collection-browsing activity.
            rootView.findViewById(R.id.demo_collection_button).setOnClickListener(new View.OnClickListener()
            {
                @Override
                public void onClick(View view) 
                {
                    Intent intent = new Intent(getActivity(), CollectionDemoActivity.class);
                    startActivity(intent);
                }
            });

            // Demonstration of navigating to external activities.
            rootView.findViewById(R.id.demo_external_activity).setOnClickListener(new View.OnClickListener()
            {
                @Override
                public void onClick(View view)
                {
                    // Create an intent that asks the user to pick a photo, but using
                    // FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET, ensures that relaunching
                    // the application from the device home screen does not return
                    // to the external activity.
                    Intent externalActivityIntent = new Intent(Intent.ACTION_PICK);
                    externalActivityIntent.setType("image/*");
                    externalActivityIntent.addFlags(
                    Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET);
                    startActivity(externalActivityIntent);
                }
            });
            return rootView;
        }
    }

    /**
     * A dummy fragment representing a section of the app, but that simply displays dummy text.
     */
    public static class DummySectionFragment extends Fragment
    {
        public static final String ARG_SECTION_NUMBER = "section_number";

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
        {
            View rootView = inflater.inflate(R.layout.fragment_section_dummy, container, false);
            Bundle args = getArguments();
            ((TextView) rootView.findViewById(android.R.id.text1)).setText(getString(R.string.dummy_section_text, args.getInt(ARG_SECTION_NUMBER)));
            return rootView;
        }
    }
    public class CustomView extends View
    {
        public CustomView(Context context)
        {
            super(context, null);
        }
    } 
}