Question: I have simply Activity which is child of ActionBarActivity class. In the method I set OnCreate supported the toolbar. For this I override the OnOptionsItemSelected, so when I press the back button was performed some action

The code looks like this:

```
    [Activity (Label = "SimplyActivity", Theme="@style/MyTheme")]           
        public class SimplyActivity : ActionBarActivity
        {
            private Toolbar toolbar;

            // ... OnCreate method
            this.toolbar = FindViewById<Toolbar>(Resource.Id.toolbar);
            SetSupportActionBar (this.toolbar);
            SupportActionBar.SetDisplayHomeAsUpEnabled (true);
            SupportActionBar.SetHomeButtonEnabled (true);

            public override bool OnOptionsItemSelected (IMenuItem item)
            {
                if (item.TitleFormatted == null) this.OnBackPressed ();
                return base.OnOptionsItemSelected (item);
            }

```

Unfortunately, as long as the toolbar is displayed correctly, this is no longer any reaction when keys are pressed back. I would add that in other activities (which uses fragments) everything works correctly.

Please help me

Answer: 
The problem turned out to be really strange. Layout, which was using the action bar had RelativeLayout. After changing to LinearLayout attribute android:gravity = "vertical", everything works correctly.

Thanks all for help
I suggest you to use this code snippet to use a custom back button in your toolbar :

First Step :
Add an icon back button into drawable folder .

Second Step :
add toolbar into your AppBarLayout like this :

```
<android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/chart_toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:popupTheme="@style/AppTheme.PopupOverlay" />

</android.support.design.widget.AppBarLayout>

```

Third Step :
in your onCreate find Views like this :

```
Toolbar toolbar = (Toolbar) findViewById(R.id.chart_toolbar);

```

4th Step :
add support action bar to your toolbar :

```
setSupportActionBar(toolbar);

if (getSupportActionBar() != null) {
        getSupportActionBar().setDisplayShowHomeEnabled(true);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
}

```

5th Step :
Add desire icon to your button :

```
toolbar.setNavigationIcon(ContextCompat.getDrawable(getApplicationContext(), R.drawable.ic_chevron_left));

```

6th Step :
set a click listener for your back button :

```
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                NavUtils.navigateUpFromSameTask(Chart.this);
            }
});

```

and finally override oncreateoptionsmenu and onoptionsitemselected methods :

```
@Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.my_menu, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {

        return true;
    }

```