navigation bug fix for previewing text files

res/layout/file_preview.xml

@@ -23,7 +23,6 @@
     android:id="@+id/top"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
-    android:background="@color/background_color"
     android:gravity="center"
     tools:context=".ui.fragment.FilePreviewFragment">
 

src/com/owncloud/android/ui/activity/FileDisplayActivity.java

@@ -178,12 +178,6 @@ public class FileDisplayActivity extends HookActivity
         mRightFragmentContainer = findViewById(R.id.right_fragment_container);
 
         // Action bar setup
-        getSupportActionBar().setHomeButtonEnabled(true);       // mandatory since Android ICS,
-        // according to the official
-        // documentation
-
-        // enable ActionBar app icon to behave as action to toggle nav drawer
-        //getSupportActionBar().setDisplayHomeAsUpEnabled(true);
         getSupportActionBar().setHomeButtonEnabled(true);
 
         // Init Fragment without UI to retain AsyncTask across configuration changes
@@ -1714,7 +1708,7 @@ public class FileDisplayActivity extends HookActivity
                 PreviewTextFragment.class.getName(), args);
         setSecondFragment(textPreviewFragment);
         updateFragmentsVisibility(true);
-        //updateNavigationElementsInActionBar(file);
+        updateActionBarTitleAndHomeButton(file);
         setFile(file);
     }