Back button to navigate tabs on main view

app/src/main/java/com/keylesspalace/tusky/MainActivity.java

@@ -43,6 +43,7 @@ import org.json.JSONObject;
 
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Stack;
 
 public class MainActivity extends BaseActivity {
     private static final String TAG = "MainActivity"; // logging tag and Volley request tag
@@ -52,6 +53,8 @@ public class MainActivity extends BaseActivity {
     private boolean notificationServiceEnabled;
     private String loggedInAccountId;
     private String loggedInAccountUsername;
+    Stack<Integer> pageHistory = new Stack<Integer>();
+    private ViewPager viewPager;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
@@ -81,16 +84,44 @@ public class MainActivity extends BaseActivity {
             getString(R.string.title_public)
         };
         adapter.setPageTitles(pageTitles);
-        ViewPager viewPager = (ViewPager) findViewById(R.id.pager);
+        viewPager = (ViewPager) findViewById(R.id.pager);
         int pageMargin = getResources().getDimensionPixelSize(R.dimen.tab_page_margin);
         viewPager.setPageMargin(pageMargin);
         Drawable pageMarginDrawable = ThemeUtils.getDrawable(this, R.attr.tab_page_margin_drawable,
                 R.drawable.tab_page_margin_dark);
         viewPager.setPageMarginDrawable(pageMarginDrawable);
         viewPager.setAdapter(adapter);
+
         TabLayout tabLayout = (TabLayout) findViewById(R.id.tab_layout);
         tabLayout.setupWithViewPager(viewPager);
 
+        tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
+            @Override
+            public void onTabSelected(TabLayout.Tab tab) {
+                viewPager.setCurrentItem(tab.getPosition());
+
+                if (pageHistory.empty()) {
+                    pageHistory.push(0);
+                }
+
+                if (pageHistory.contains(tab.getPosition())) {
+                    pageHistory.remove(pageHistory.indexOf(tab.getPosition()));
+                }
+
+                pageHistory.push(tab.getPosition());
+            }
+
+            @Override
+            public void onTabUnselected(TabLayout.Tab tab) {
+
+            }
+
+            @Override
+            public void onTabReselected(TabLayout.Tab tab) {
+
+            }
+        });
+
         // Retrieve notification update preference.
         SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this);
         notificationServiceEnabled = preferences.getBoolean("pullNotifications", true);
@@ -218,6 +249,17 @@ public class MainActivity extends BaseActivity {
                 return true;
             }
         }
+
         return super.onOptionsItemSelected(item);
     }
+
+    @Override
+    public void onBackPressed() {
+        if(pageHistory.empty()) {
+            super.onBackPressed();
+        } else {
+            pageHistory.pop();
+            viewPager.setCurrentItem(pageHistory.lastElement());
+        }
+    }
 }

app/src/main/res/layout/item_follow.xml

@@ -83,7 +83,7 @@
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:id="@+id/notification_username"
-                android:textColor="?attr/status_text_color_secondary" />
+                android:textColor="?android:textColorSecondary" />
 
             <Space
                 android:layout_width="wrap_content"