Partial implementation for Issue 1059. Doesn't help those without

physical keyboards, though, and should be modified to only re-setup
pushers.  Current implementation causes a wasteful reschedule of
polling.

Also gets the help Toast for the folder up-to-date after the
FolderList/MessageList split.

res/values/strings.xml

@@ -594,7 +594,14 @@ Welcome to K-9 Mail setup.  K-9 is an open source mail client for Android origin
     <string name="message_list_help_key">Del (or D) - Delete\u000AR -
     Reply\u000AA - Reply All\u000AC - Compose\u000AF - Forward\u000aM - 
     Move\u000AY - Copy\u000AG - Star\u000AO - Sort type\u000AI - Sort order\u000AQ
-    - Return to Accounts\u000AS - Select/deselect</string>
+    - Return to Folders\u000AS - Select/deselect</string>
+    
+      <string name="folder_list_help_key">1 - Display only 1st Class folders\u000A
+      2 - Display 1st and 2nd Class folders\u000A
+      3 - Display all except 2nd Class folders\u000A
+      4 - Display all folders\u000A
+      Q - Return to Accounts\u000A
+      S - Edit Account Settings</string>
 
     <string name="account_settings_signature__location_label">Signature position</string>
     <string name="account_settings_signature__location_before_quoted_text">Before quoted messages</string>

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

@@ -19,12 +19,14 @@ import android.widget.*;
 import android.widget.AdapterView.AdapterContextMenuInfo;
 import android.widget.AdapterView.OnItemClickListener;
 import com.fsck.k9.*;
+import com.fsck.k9.Account.FolderMode;
 import com.fsck.k9.activity.setup.AccountSettings;
 import com.fsck.k9.activity.setup.FolderSettings;
 import com.fsck.k9.mail.Folder;
 import com.fsck.k9.mail.Message;
 import com.fsck.k9.mail.MessagingException;
 import com.fsck.k9.mail.Store;
+import com.fsck.k9.service.MailService;
 
 import java.util.ArrayList;
 import java.util.Collections;
@@ -368,16 +370,46 @@ public class FolderList extends K9ListActivity
 
             case KeyEvent.KEYCODE_H:
             {
-                Toast toast = Toast.makeText(this, R.string.message_list_help_key, Toast.LENGTH_LONG);
+                Toast toast = Toast.makeText(this, R.string.folder_list_help_key, Toast.LENGTH_LONG);
                 toast.show();
                 return true;
             }
+            
+            case KeyEvent.KEYCODE_1:
+            {
+                setDisplayMode(FolderMode.FIRST_CLASS);
+                return true;
+            }
+            case KeyEvent.KEYCODE_2:
+            {
+                setDisplayMode(FolderMode.FIRST_AND_SECOND_CLASS);
+                return true;
+            }
+            case KeyEvent.KEYCODE_3:
+            {
+                setDisplayMode(FolderMode.NOT_SECOND_CLASS);
+                return true;
+            }
+            case KeyEvent.KEYCODE_4:
+            {
+                setDisplayMode(FolderMode.ALL);
+                return true;
+            }
         }//switch
 
 
         return super.onKeyDown(keyCode, event);
     }//onKeyDown
 
+    private void setDisplayMode(FolderMode newMode)
+    {
+        mAccount.setFolderDisplayMode(newMode);
+        mAccount.save(Preferences.getPreferences(this));
+        MailService.actionReschedule(this, null);  // TODO: really should just refresh pushers
+        onRefresh(false);
+    }
+    
+    
     private void onRefresh(final boolean forceRemote)
     {