Don't crash when switching to subtasks mode

astrid/src/com/todoroo/astrid/activity/TaskListActivity.java

@@ -208,7 +208,7 @@ public class TaskListActivity extends AstridActivity implements MainMenuListener
     @Override
     public void setupTasklistFragmentWithFilterAndCustomTaskList(Filter filter, Bundle extras, Class<?> customTaskList) {
         if (fragmentLayout == LAYOUT_SINGLE) {
-            tlfPager.showFilter(filter);
+            tlfPager.showFilterWithCustomTaskList(filter, customTaskList);
         } else {
             super.setupTasklistFragmentWithFilterAndCustomTaskList(filter, extras, customTaskList);
         }

astrid/src/com/todoroo/astrid/activity/TaskListFragment.java

@@ -1202,10 +1202,10 @@ public class TaskListFragment extends ListFragment implements OnScrollListener,
 
     protected void toggleDragDrop(boolean newState) {
         if(newState)
-            ((AstridActivity)getActivity()).setupTasklistFragmentWithFilterAndCustomTaskList(null,
+            ((AstridActivity)getActivity()).setupTasklistFragmentWithFilterAndCustomTaskList(filter,
                     extras, SubtasksListFragment.class);
         else
-            ((AstridActivity)getActivity()).setupTasklistFragmentWithFilterAndCustomTaskList(null,
+            ((AstridActivity)getActivity()).setupTasklistFragmentWithFilterAndCustomTaskList(filter,
                     extras, TaskListFragment.class);
     }
 

astrid/src/com/todoroo/astrid/adapter/TaskListFragmentPagerAdapter.java

@@ -16,6 +16,7 @@ import com.todoroo.astrid.api.FilterWithCustomIntent;
 public class TaskListFragmentPagerAdapter extends FragmentStatePagerAdapter implements FilterDataSourceChangedListener {
 
     private final HashMap<Integer, Fragment> positionToFragment;
+    private final HashMap<Filter, Class<?>> customTaskLists;
 
     private final FilterAdapter filterAdapter; // Shares an adapter instance with the filter list fragment
 
@@ -24,6 +25,7 @@ public class TaskListFragmentPagerAdapter extends FragmentStatePagerAdapter impl
         this.filterAdapter = filterAdapter;
         filterAdapter.setDataSourceChangedListener(this);
         positionToFragment = new HashMap<Integer, Fragment>();
+        customTaskLists = new HashMap<Filter, Class<?>>();
     }
 
     @Override
@@ -81,9 +83,21 @@ public class TaskListFragmentPagerAdapter extends FragmentStatePagerAdapter impl
         return filterAdapter.getCount();
     }
 
+    public void setCustomTaskListForFilter(Filter f, Class<?> customTaskList) {
+        customTaskLists.put(f, customTaskList);
+        notifyDataSetChanged();
+    }
+
+    public void clearCustomTaskListForFilter(Filter f) {
+        customTaskLists.remove(f);
+    }
+
     private Fragment getFragmentForFilter(Filter filter) {
         Bundle extras = getExtrasForFilter(filter);
-        return TaskListFragment.instantiateWithFilterAndExtras(filter, extras);
+        Class<?> customList = customTaskLists.get(filter);
+        if (customList == null)
+            customList = TaskListFragment.class;
+        return TaskListFragment.instantiateWithFilterAndExtras(filter, extras, customList);
     }
 
     // Constructs extras corresponding to the specified filter that can be used as arguments to the fragment

astrid/src/com/todoroo/astrid/ui/TaskListFragmentPager.java

@@ -31,6 +31,12 @@ public class TaskListFragmentPager extends ViewPager {
         showFilter(adapter.addOrLookup(f));
     }
 
+    public void showFilterWithCustomTaskList(Filter f, Class<?> customTaskList) {
+        TaskListFragmentPagerAdapter adapter = (TaskListFragmentPagerAdapter) getAdapter();
+        adapter.setCustomTaskListForFilter(f, customTaskList);
+        showFilter(adapter.addOrLookup(f));
+    }
+
     /**
      * Show the filter at the supplied index, with animation
      * @param index