Add "Mark all as read" action to message list

res/menu/message_list_option.xml

@@ -175,6 +175,12 @@
         android:showAsAction="never"
         android:title="@string/batch_select_all"/>
 
+    <!-- MessageList -->
+    <item
+        android:id="@+id/mark_all_as_read"
+        android:showAsAction="never"
+        android:title="@string/mark_all_as_read"/>
+
     <!-- MessageList -->
     <item
         android:id="@+id/send_messages"

res/values/strings.xml

@@ -1145,4 +1145,6 @@ Please submit bug reports, contribute new features and ask questions at
     <string name="last_refresh_time_format">Refreshed <xliff:g id="formatted_time">%s</xliff:g></string>
     <string name="last_refresh_time_format_with_push">Refreshed <xliff:g id="time_with_preposition">%s</xliff:g> (Push active)</string>
     <string name="preposition_for_date">on <xliff:g id="date">%s</xliff:g></string>
+
+    <string name="mark_all_as_read">Mark all as read</string>
 </resources>

src/com/fsck/k9/activity/MessageList.java

@@ -805,6 +805,10 @@ public class MessageList extends K9FragmentActivity implements MessageListFragme
                 mMessageListFragment.onRemoteSearch();
                 return true;
             }
+            case R.id.mark_all_as_read: {
+                mMessageListFragment.markAllAsRead();
+                return true;
+            }
             // MessageView
             case R.id.next_message: {
                 showNextMessage();
@@ -1032,9 +1036,12 @@ public class MessageList extends K9FragmentActivity implements MessageListFragme
             menu.findItem(R.id.select_all).setVisible(false);
             menu.findItem(R.id.send_messages).setVisible(false);
             menu.findItem(R.id.expunge).setVisible(false);
+            menu.findItem(R.id.mark_all_as_read).setVisible(false);
         } else {
             menu.findItem(R.id.set_sort).setVisible(true);
             menu.findItem(R.id.select_all).setVisible(true);
+            menu.findItem(R.id.mark_all_as_read).setVisible(
+                    mMessageListFragment.isMarkAllAsReadSupported());
 
             if (!mMessageListFragment.isSingleAccountMode()) {
                 menu.findItem(R.id.expunge).setVisible(false);

src/com/fsck/k9/fragment/MessageListFragment.java

@@ -3442,4 +3442,14 @@ public class MessageListFragment extends SherlockFragment implements OnItemClick
     public boolean isInitialized() {
         return mInitialized;
     }
+
+    public boolean isMarkAllAsReadSupported() {
+        return (isSingleAccountMode() && isSingleFolderMode());
+    }
+
+    public void markAllAsRead() {
+        if (isMarkAllAsReadSupported()) {
+            mController.markAllMessagesRead(mAccount, mFolderName);
+        }
+    }
 }