black fragment content when changing tab back

Question

I have a fragment activity with TabHost and ViewPager inside it. There are two tabs for the activity: the List tab and the Map tab. On the List tab I've got list of my data (some institutions) and on the Map tab (using Google Maps API) I am displaying that institutions on the map with markers.

When activity is opened default tab is List. Swiping from right to left, or selecting Map tab brings me to the Map with markers.

The problem is, when I'm selecting the List tab again I've got a black content in stead of ListView and it's items. However, when from the List tab I select the Map tab again, Map shows correctly.

Here is activity source:

public class Institutions extends FragmentActivity {

public static final int TAB_LIST = 0;
public static final int TAB_MAP = 1;

private TabHost mTabHost;
private ViewPager mViewPager;
private TabsAdapter mTabsAdapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.institutions);

    mTabHost = (TabHost) findViewById(android.R.id.tabhost);
    mTabHost.setup();

    mViewPager = (ViewPager) findViewById(R.id.pager);
    mViewPager.setOffscreenPageLimit(1);

    mTabsAdapter = new TabsAdapter(this, mTabHost, mViewPager);

    View v = createTab(TAB_LIST);

    mTabsAdapter.addTab(mTabHost.newTabSpec("list").setIndicator(v),
            InstitutionList.class, null);

    v = createTab(TAB_MAP);

    mTabsAdapter.addTab(mTabHost.newTabSpec("map").setIndicator(v),
            InstitutionMap.class, null);

    TextView activity_title = (TextView) findViewById(R.id.activity_title);

    activity_title.setText(getIntent().getStringExtra(
            Institution.INSTITUTION_TITLE));
}

private View createTab(int type) {
    View v = getLayoutInflater().inflate(R.layout.tab, null);

    TextView label = (TextView) v.findViewById(R.id.label);
    ImageView icon = (ImageView) v.findViewById(R.id.icon);

    icon.setVisibility(View.GONE);

    icon.getLayoutParams().width = 1;
    icon.getLayoutParams().height = 1;

    switch (type) {
    case TAB_LIST:
        label.setText(getString(R.string.list_title));
        break;

    case TAB_MAP:
        label.setText(getString(R.string.map_title));
        break;

    default:
        break;
    }

    return v;
}
}

Here is the source for TabsAdapter:

public class TabsAdapter extends FragmentStatePagerAdapter implements
    TabHost.OnTabChangeListener, ViewPager.OnPageChangeListener {
private final Context mContext;
private final TabHost mTabHost;
private final ViewPager mViewPager;
private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();

static final class TabInfo {
    private final Class<? extends Fragment> clss;
    private final Bundle args;

    private Tab tab;

    TabInfo(Class<? extends Fragment> _class, Bundle _args) {
        clss = _class;
        args = _args;
        tab = null;
    }
}

static class TabFactory implements TabHost.TabContentFactory {
    private final Context mContext;

    public TabFactory(Context context) {
        mContext = context;
    }

    @Override
    public View createTabContent(String tag) {
        View v = new View(mContext);
        v.setMinimumWidth(0);
        v.setMinimumHeight(0);
        return v;
    }
}

public TabsAdapter(FragmentActivity activity, TabHost tabHost,
        ViewPager pager) {
    super(activity.getSupportFragmentManager());
    mContext = activity;
    mTabHost = tabHost;
    mViewPager = pager;
    mTabHost.setOnTabChangedListener(this);
    mViewPager.setAdapter(this);
    mViewPager.setOnPageChangeListener(this);
}

public void addTab(TabHost.TabSpec tabSpec, Class<? extends Fragment> clss,
        Bundle args) {
    tabSpec.setContent(new TabFactory(mContext));

    TabInfo info = new TabInfo(clss, args);
    mTabs.add(info);
    mTabHost.addTab(tabSpec);
    notifyDataSetChanged();
}

@Override
public int getItemPosition(Object object) {
    return POSITION_NONE;
}

@Override
public int getCount() {
    return mTabs.size();
}

@Override
public Fragment getItem(int position) {
    TabInfo info = mTabs.get(position);
    if (info.tab == null) {
        info.tab = (Tab) Fragment.instantiate(mContext,
                info.clss.getName(), info.args);
    }

    return info.tab;
}

@Override
public void onTabChanged(String tabId) {
    int position = mTabHost.getCurrentTab();
    mViewPager.setCurrentItem(position);

    for (int i = 0; i < getCount(); i++) {
        if (i == position)
            continue;

        Tab t = mTabs.get(i).tab;

        if (t != null) {
            t.onTabUnselected();
        }
    }
}

@Override
public void onPageScrolled(int position, float positionOffset,
        int positionOffsetPixels) {
}

@Override
public void onPageSelected(int position) {
    TabWidget widget = mTabHost.getTabWidget();
    int oldFocusability = widget.getDescendantFocusability();
    widget.setDescendantFocusability(ViewGroup.FOCUS_BLOCK_DESCENDANTS);
    mTabHost.setCurrentTab(position);
    widget.setDescendantFocusability(oldFocusability);
}

@Override
public void onPageScrollStateChanged(int state) {
}
}