Fix (commons-app#4148) Issues on theme change

* fixed themeChange crashes

* fixed comments

* Overlooked the title bar

Author: 4D17Y4

app/src/main/java/fr/free/nrw/commons/bookmarks/BookmarkListRootFragment.java

@@ -38,6 +38,10 @@ public class BookmarkListRootFragment extends CommonsDaggerSupportFragment imple
   @BindView(R.id.explore_container)
   FrameLayout container;
 
+  public BookmarkListRootFragment(){
+    //empty constructor necessary otherwise crashes on recreate
+  }
+
   public BookmarkListRootFragment(Bundle bundle, BookmarksPagerAdapter bookmarksPagerAdapter) {
     String title = bundle.getString("categoryName");
     int order = bundle.getInt("order");
@@ -65,7 +69,9 @@ public View onCreateView(@NonNull final LayoutInflater inflater, @Nullable final
   @Override
   public void onViewCreated(@NonNull final View view, @Nullable final Bundle savedInstanceState) {
     super.onViewCreated(view, savedInstanceState);
-    setFragment(listFragment, mediaDetails);
+    if(savedInstanceState==null) {
+      setFragment(listFragment, mediaDetails);
+    }
   }
 
   public void setFragment(Fragment fragment, Fragment otherFragment) {

app/src/main/java/fr/free/nrw/commons/contributions/MainActivity.java

@@ -113,7 +113,11 @@ public void onCreate(Bundle savedInstanceState) {
             setTitle(getString(R.string.explore_tab_title_mobile));
             setUpLoggedOutPager();
         } else {
-            setTitle(getString(R.string.contributions_fragment));
+            if(savedInstanceState == null){
+                //starting a fresh fragment.
+                setTitle(getString(R.string.contributions_fragment));
+                loadFragment(ContributionsFragment.newInstance(),false);
+            }
             setUpPager();
             initMain();
         }
@@ -124,30 +128,31 @@ public void setSelectedItemId(int id) {
     }
 
     private void setUpPager() {
-        loadFragment(ContributionsFragment.newInstance());
         tabLayout.setOnNavigationItemSelectedListener(item -> {
             if (!item.getTitle().equals("More")) {
                 // do not change title for more fragment
                 setTitle(item.getTitle());
             }
             Fragment fragment = NavTab.of(item.getOrder()).newInstance();
-            return loadFragment(fragment);
+            return loadFragment(fragment,true);
         });
     }
 
     private void setUpLoggedOutPager() {
-        loadFragment(ExploreFragment.newInstance());
+        loadFragment(ExploreFragment.newInstance(),false);
         tabLayout.setOnNavigationItemSelectedListener(item -> {
             if (!item.getTitle().equals("More")) {
                 // do not change title for more fragment
                 setTitle(item.getTitle());
             }
             Fragment fragment = NavTabLoggedOut.of(item.getOrder()).newInstance();
-            return loadFragment(fragment);
+            return loadFragment(fragment,true);
         });
     }
 
-    private boolean loadFragment(Fragment fragment) {
+    private boolean loadFragment(Fragment fragment,boolean showBottom ) {
+        //showBottom so that we do not show the bottom tray again when constructing
+        //from the saved instance state.
         if (fragment instanceof ContributionsFragment) {
             if (activeFragment == ActiveFragment.CONTRIBUTIONS) { // Do nothing if same tab
                 return true;
@@ -172,7 +177,7 @@ private boolean loadFragment(Fragment fragment) {
             }
             bookmarkFragment = (BookmarkFragment) fragment;
             activeFragment = ActiveFragment.BOOKMARK;
-        } else if (fragment == null) {
+        } else if (fragment == null && showBottom) {
             if (applicationKvStore.getBoolean("login_skipped") == true) { // If logged out, more sheet is different
                 MoreBottomSheetLoggedOutFragment bottomSheet = new MoreBottomSheetLoggedOutFragment();
                 bottomSheet.show(getSupportFragmentManager(),

app/src/main/java/fr/free/nrw/commons/explore/ExploreListRootFragment.java

@@ -34,6 +34,10 @@ public class ExploreListRootFragment extends CommonsDaggerSupportFragment implem
   @BindView(R.id.explore_container)
   FrameLayout container;
 
+  public ExploreListRootFragment(){
+    //empty constructor necessary otherwise crashes on recreate
+  }
+
   public ExploreListRootFragment(Bundle bundle) {
     String title = bundle.getString("categoryName");
     listFragment = new CategoriesMediaFragment();
@@ -55,7 +59,9 @@ public View onCreateView(@NonNull final LayoutInflater inflater, @Nullable final
   @Override
   public void onViewCreated(@NonNull final View view, @Nullable final Bundle savedInstanceState) {
     super.onViewCreated(view, savedInstanceState);
-    setFragment(listFragment, mediaDetails);
+    if(savedInstanceState == null) {
+      setFragment(listFragment, mediaDetails);
+    }
   }
 
   public void setFragment(Fragment fragment, Fragment otherFragment) {