Mitter/mitterlib/ui/ui_pygtk.py

#!/usr/bin/python
# -*- coding: utf-8 -*-

# Mitter, a Maemo client for Twitter.
# Copyright (C) 2007, 2008  Julio Biason, Deepak Sarda
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

import gtk
import gobject

gobject.threads_init()

import logging
import threading
import Queue
import re
import urllib2

from mitterlib.ui.helpers.image_helpers import find_image
from mitterlib import htmlize

from mitterlib.constants import gpl_3, version
from mitterlib.ui.helpers import timesince

# Constants

_log = logging.getLogger('ui.pygtk')

URL_RE = re.compile(r'(https?://[^\s\n\r]+)', re.I)


# ----------------------------------------------------------------------
# Helper Functions (not related to objects or that don't need direct access to
# the objects contents.)
# ----------------------------------------------------------------------

def _buffer_text(text_buffer):
    """Return the content of a gtk.TextBuffer."""
    start = text_buffer.get_start_iter()
    end = text_buffer.get_end_iter()

    text = text_buffer.get_text(start, end, include_hidden_chars=False)

    return text

# ----------------------------------------------------------------------
# Threading related objects.
# These classes are based on the code available at http://gist.github.com/51686
# (c) 2008, John Stowers <john.stowers@gmail.com>
# ----------------------------------------------------------------------

class _IdleObject(gobject.GObject):
    """
    Override gobject.GObject to always emit signals in the main thread
    by emmitting on an idle handler
    """
    def __init__(self):
        gobject.GObject.__init__(self)

    def emit(self, *args):
        gobject.idle_add(gobject.GObject.emit, self, *args)


class _WorkerThread(threading.Thread, _IdleObject):
    """
    A single working thread.
    """
    __gsignals__ = {
            "completed": (
                gobject.SIGNAL_RUN_LAST,
                gobject.TYPE_NONE,
                (gobject.TYPE_PYOBJECT,)),  # list/networkdata
            "exception": (
                gobject.SIGNAL_RUN_LAST,
                gobject.TYPE_NONE,
                (gobject.TYPE_PYOBJECT,))   # The exception
            }

    def __init__(self, function, *args, **kwargs):
        threading.Thread.__init__(self)
        _IdleObject.__init__(self)
        self._function = function
        self._args = args
        self._kwargs = kwargs

    def run(self):
        # call the function
        _log.debug('Thread %s calling %s', self.name, str(self._function))

        args = self._args
        kwargs = self._kwargs

        try:
            result = self._function(*args, **kwargs)
        except Exception, exc:  # Catch ALL exceptions
            # TODO: Check if this catch all warnins too!
            _log.debug('Exception %s', str(exc))
            self.emit("exception", exc)
            return

        _log.debug('Thread %s completed', self.name)

        self.emit("completed", result)
        return


class _ThreadManager(object):
    """Manages the threads."""

    def __init__(self, max_threads=2):
        """Start the thread pool. The number of threads in the pool is defined
        by `pool_size`, defaults to 2."""
        self._max_threads = max_threads
        self._thread_pool = []
        self._running = []
        self._thread_id = 0

        return

    def _remove_thread(self, widget, arg=None):
        """Called when the thread completes. We remove it from the thread list
        (dictionary, actually) and start the next thread (if there is one)."""

        # not actually a widget. It's the object that emitted the signal, in
        # this case, the _WorkerThread object.
        thread_id = widget.name

        _log.debug('Thread %s completed, %d threads in the queue', thread_id,
                len(self._thread_pool))

        self._running.remove(thread_id)

        if self._thread_pool:
            if len(self._running) < self._max_threads:
                next = self._thread_pool.pop()
                _log.debug('Dequeuing thread %s', next.name)
                self._running.append(next.name)
                next.start()

        return

    def add_work(self, complete_cb, exception_cb, func, *args, **kwargs):
        """Add a work to the thread list. `complete_cb` is the function to be
        called with the result of the work. `exception_cb` is the function to
        be called if there are any exceptions raised. Note that, once the
        work is complete, one of those will be called, not both. `func` is the
        function to be called in the secondary threads. `args` and `kwargs`
        are parameters passed to the function."""

        thread = _WorkerThread(func, *args, **kwargs)
        thread_id = '%s' % (self._thread_id)

        thread.connect('completed', complete_cb)
        thread.connect('completed', self._remove_thread)
        thread.connect('exception', exception_cb)
        thread.setName(thread_id)

        if len(self._running) < self._max_threads:
            # immediatelly start the thread
            self._running.append(thread_id)
            thread.start()
        else:
            # add the thread to the queue
            running_names = ', '.join(self._running)
            _log.debug('Threads %s running, adding %s to the queue',
                    running_names, thread_id)
            self._thread_pool.append(thread)

        self._thread_id += 1
        return


# ----------------------------------------------------------------------
# Mitter interface object
# ----------------------------------------------------------------------

class Interface(object):
    """Linux/GTK interface for Mitter."""

    NAMESPACE = 'pygtk'

    # ------------------------------------------------------------
    # Widget creation functions
    # ------------------------------------------------------------
    def _create_main_window(self):
        """Returns the object with the main window and the attached
        widgets."""
        main_window = gtk.Window(gtk.WINDOW_TOPLEVEL)

        initial_width = int(self._options[self.NAMESPACE]['width'])
        initial_height = int(self._options[self.NAMESPACE]['height'])
        _log.debug('Initial size: %d x %d', initial_width, initial_height)

        initial_x = int(self._options[self.NAMESPACE]['position_x'])
        initial_y = int(self._options[self.NAMESPACE]['position_y'])
        _log.debug('Initial position: %d x %d', initial_x, initial_y)

        main_window.set_title('Mitter')
        main_window.set_size_request(450, 300) # very small minimal size
        main_window.resize(initial_width, initial_height)
        main_window.move(initial_x, initial_y)

        if self._app_icon:
            main_window.set_icon_from_file(self._app_icon)

        main_window.connect('destroy', self._quit_app)
        main_window.connect('delete-event', self._quit_app)
        main_window.connect('size-request', self._grid_resize)

        grid = self._create_grid()
        (menu, toolbar, accelerators) = self._create_menu_and_toolbar()
        update_field = self._create_update_box()
        self._statusbar = self._create_statusbar()

        update_box = gtk.VPaned()
        update_box.pack1(grid, resize=True, shrink=False)
        update_box.pack2(update_field, resize=False, shrink=True)
        # TODO: Save the size of the update box in the config file.

        box = gtk.VBox(False, 1)
        box.pack_start(menu, False, True, 0)
        box.pack_start(toolbar, False, False, 0)
        box.pack_start(update_box, True, True, 0)
        box.pack_start(self._statusbar, False, False, 0)
        main_window.add(box)
        main_window.add_accel_group(accelerators)

        return main_window

    def _create_grid(self):
        """Add the displaying grid."""
        # Store NetworkData objects only
        grid_store = gtk.ListStore(object)
        grid_store.set_sort_column_id(0, gtk.SORT_ASCENDING)
        grid_store.set_sort_func(0, self._order_datetime)

        self._grid = gtk.TreeView(grid_store)
        self._grid.set_property('headers-visible', False)
        self._grid.set_rules_hint(True)  # change color for each row

        user_renderer = gtk.CellRendererPixbuf()
        user_column = gtk.TreeViewColumn('User', user_renderer)
        user_column.set_fixed_width(48) # avatar size (we resize to 48x48)
        user_column.set_sizing(gtk.TREE_VIEW_COLUMN_FIXED)
        user_column.set_cell_data_func(user_renderer,
                self._cell_renderer_user)

        message_renderer = gtk.CellRendererText()
        message_renderer.set_property('wrap-mode', gtk.WRAP_WORD)
        message_renderer.set_property('wrap-width', 200)
        message_column = gtk.TreeViewColumn('Message',
                message_renderer)
        message_column.set_cell_data_func(message_renderer,
                self._cell_renderer_message)

        self._grid.append_column(user_column)
        self._grid.append_column(message_column)

        self._grid.set_resize_mode(gtk.RESIZE_IMMEDIATE)
        self._grid.connect('cursor-changed', self._message_selected)
        #self._grid.connect('row-activated', self.open_post)
        #self.grid.connect('button-press-event', self.click_post)
        #self.grid.connect('popup-menu',
        #        lambda view: self.show_post_popup(view, None))

        scrolled_window = gtk.ScrolledWindow()
        scrolled_window.set_policy(gtk.POLICY_NEVER, gtk.POLICY_ALWAYS)
        scrolled_window.add(self._grid)

        return scrolled_window

    def _create_menu_and_toolbar(self):
        """Create the main menu and the toolbar."""
        
        # UI elements
        ui_elements = '''
        <ui>
          <toolbar name="MainToolbar">
            <toolitem action="Refresh" />
            <toolitem action="Clear" />
            <separator />
            <toolitem action="Delete" />
            <toolitem action="Reply" />
            <toolitem action="Repost" />
            <separator />
            <toolitem action="Settings" />
            <toolitem action="Quit" />
          </toolbar>
          <menubar name="MainMenu">
            <menu action="File">
              <menuitem action="Quit" />
            </menu>
            <menu action="Edit">
              <menuitem action="Refresh" />
              <menuitem action="Clear" />
              <separator />
              <menuitem action="Update" />
              <menuitem action="Cancel" />
              <menuitem action="ShrinkURL" />
              <menuitem action="MuteNotify" />
              <separator />
              <menuitem action="Settings" />
            </menu>
            <menu action="Message">
              <menuitem action="Delete" />
              <menuitem action="Reply" />
              <menuitem action="Repost" />
            </menu>
            <menu action="Help">
              <menuitem action="About" />
            </menu>
          </menubar>
        </ui>
        '''

        # The group with all actions; we are going to split them using the
        # definitions inside the XML.
        action_group = gtk.ActionGroup('Mitter')

        # Actions related to the UI elements above
        # Top-level menu actions
        file_action = gtk.Action('File', '_File', 'File', None)
        action_group.add_action(file_action)

        edit_action = gtk.Action('Edit', '_Edit', 'Edit', None)
        action_group.add_action(edit_action)
        
        message_action = gtk.Action('Message', '_Message', 
                'Message related options', None)
        action_group.add_action(message_action)
        
        help_action = gtk.Action('Help', '_Help', 'Help', None)
        action_group.add_action(help_action)
        
        # File actions
        quit_action = gtk.Action('Quit', '_Quit',
                'Exit Mitter', gtk.STOCK_QUIT)
        quit_action.connect('activate', self._quit_app)
        action_group.add_action_with_accel(quit_action, None)
        
        # Edit actions
        refresh_action = gtk.Action('Refresh', '_Refresh',
                'Update the listing', gtk.STOCK_REFRESH)
        refresh_action.connect('activate', self._refresh)
        action_group.add_action_with_accel(refresh_action, None)

        self._update_action = gtk.Action('Update', '_Update',
                'Update your status', gtk.STOCK_ADD)
        self._update_action.set_property('sensitive', False)
        self._update_action.connect('activate', self._update_status)
        action_group.add_action_with_accel(self._update_action,
                '<Ctrl>Return')
                
        self._cancel_action = gtk.Action('Cancel', '_Cancel',
                'Cancel the update', gtk.STOCK_CANCEL)
        self._cancel_action.set_property('sensitive', False)
        self._cancel_action.connect('activate', self._clear_text)
        action_group.add_action_with_accel(self._cancel_action,
                '<Ctrl>Escape')
                
        clear_action = gtk.Action('Clear', '_Clear', 
                'Clear the message list', gtk.STOCK_CLEAR)
        clear_action.connect('activate', self._clear_posts)
        action_group.add_action_with_accel(clear_action, None)

        #shrink_url_action = gtk.Action('ShrinkURL', 'Shrink _URL',
        #        'Shrink selected URL', gtk.STOCK_EXECUTE)
        #shrink_url_action.connect('activate', self.shrink_url)
        #self.action_group.add_action_with_accel(shrink_url_action, '<Ctrl>u')

        #mute_action = gtk.ToggleAction('MuteNotify', '_Mute Notifications',
        #        'Mutes notifications on new tweets', gtk.STOCK_MEDIA_PAUSE)
        #mute_action.set_active(False)
        #self.action_group.add_action_with_accel(mute_action, '<Ctrl>m')

        settings_action = gtk.Action('Settings', '_Settings',
                'Settings', gtk.STOCK_PREFERENCES)
        #settings_action.connect('activate', self.show_settings)
        action_group.add_action(settings_action)
        
        # Message actions
        self._delete_action = gtk.Action('Delete', '_Delete', 
                'Delete a post', gtk.STOCK_DELETE)
        self._delete_action.set_property('sensitive', False)
        self._delete_action.connect('activate', self._delete_message)
        action_group.add_action_with_accel(self._delete_action, 'Delete')
        # TODO: Check the accelerator
        
        self._reply_action = gtk.Action('Reply', '_Reply', 
                "Send a response to someone's else message", gtk.STOCK_REDO)
        self._reply_action.set_property('sensitive', False)
        # TODO: Connect
        # TODO: Connecting function should indicate in the status bar that
        # a reply will be made
        action_group.add_action_with_accel(self._reply_action, '<Ctrl>r')
        
        # TODO: Find a better word (non-network related) to this
        self._repost_action = gtk.Action('Repost', 'Re_post',
                "Put someone's else message on your timeline", 
                gtk.STOCK_CONVERT)
        self._repost_action.set_property('sensitive', False)
        # TODO: Connect
        # TODO: Connecting function should indicate in the status bar that
        # a repost will be made.
        action_group.add_action_with_accel(self._repost_action, '<Ctrl>t')

        # Help actions
        about_action = gtk.Action('About', '_About', 'About Mitter',
                gtk.STOCK_ABOUT)
        about_action.connect('activate', self._show_about)
        action_group.add_action(about_action)

        # definition of the UI
        uimanager = gtk.UIManager()
        uimanager.insert_action_group(action_group, 0)
        uimanager.add_ui_from_string(ui_elements)

        main_menu = uimanager.get_widget('/MainMenu')
        main_toolbar = uimanager.get_widget('/MainToolbar')

        return (main_menu, main_toolbar, uimanager.get_accel_group())

    def _create_update_box(self):
        """Create the widgets related to the update box"""
        self._update_text = gtk.TextView()
        self._update_text.set_property('wrap-mode', gtk.WRAP_WORD)
        text_buffer = self._update_text.get_buffer()
        text_buffer.connect('changed', self._count_chars)

        self._update_button = gtk.Button(label='Send')
        self._update_button.connect('clicked', self._update_status)
        self._update_button.set_property('sensitive', False)
        
        self._cancel_button = gtk.Button(label='Cancel')
        self._cancel_button.connect('clicked', self._clear_text)
        self._cancel_button.set_property('sensitive', False)
        
        info_box = gtk.HBox(True, 0)
        self._count_label = gtk.Label()
        self._count_label.set_justify(gtk.JUSTIFY_LEFT)
        self._reply_label = gtk.Label()
        
        info_box.pack_start(self._count_label, expand=True, fill=True)
        info_box.pack_start(self._reply_label, expand=True, fill=True)
        
        self._count_chars(text_buffer)
        
        update_box = gtk.HBox(False, 0)
        update_box.pack_start(self._update_text, expand=True, fill=True,
                padding=0)
        update_box.pack_start(self._update_button, expand=False, fill=False,
                padding=0)
        update_box.pack_start(self._cancel_button, expand=False, fill=False, 
                padding=0)

        update_area = gtk.VBox(True, 0)
        update_area.pack_start(info_box)
        update_area.pack_start(update_box)

        """ Spell checking the update box """
        spell_check_enabled = self._options[self.NAMESPACE]['spell_check']
        if spell_check_enabled:
            try:
                import gtkspell
                import locale
                self.spell_check_support = True
                language = locale.getlocale()[0]
                self.spell_check = gtkspell.Spell(self._update_text, language)
                _log.debug('Spell checking turned on with language: %s' \
                    % (language))
            except:
                self._options[self.NAMESPACE]['spell_check'] = False
                self.spell_check_support = False
                _log.debug('Error initializing spell checking: ' \
                    'spell checking disabled')

        return update_area

    def _create_statusbar(self):
        """Create the statusbar."""
        statusbar = gtk.Statusbar()
        self._statusbar_context = statusbar.get_context_id('Mitter')
        return statusbar

    def _show_about(self, widget):
        """Show the about dialog."""
        about_window = gtk.AboutDialog()
        about_window.set_name('Mitter')
        about_window.set_version(version)
        about_window.set_copyright('2007-2009 Mitter Contributors')
        about_window.set_license(gpl_3)
        about_window.set_website('http://code.google.com/p/mitter')
        about_window.set_website_label('Mitter on GoogleCode')
        about_window.set_authors([
            'Main developers:',
            'Julio Biason',
            'Deepak Sarda',
            'Gerald Kaszuba',
            ' ',
            'And patches from:',
            'Santiago Gala',
            'Sugree Phatanapherom',
            'Kristian Rietveld',
            '"Wiennat"',
            'Philip Reynolds',
            'Greg McIntyre',
            '"Alexander"'])
        if self._app_icon:
            _log.debug('Icon: %s', self._app_icon)
            about_window.set_logo(gtk.gdk.pixbuf_new_from_file(
                self._app_icon))
        about_window.run()
        about_window.hide()

    # ------------------------------------------------------------
    # Cell rendering functions
    # ------------------------------------------------------------
    def _cell_renderer_user(self, column, cell, store, position):
        """Callback for the user column. Used to created the pixbuf of the
        userpic."""

        data = store.get_value(position, 0)
        pic = data.avatar
        if not pic in self._avatars:
            self._threads.add_work(self._post_download_pic,
                    self._exception_download_pic,
                    self._download_pic,
                    pic)

            # set the user avatar to the default image, so it won't get queued
            # again. Once downloaded, the _post_download_pic will update the
            # image and force a redraw.
            self._avatars[pic] = self._default_pixmap

        cell.set_property('pixbuf', self._avatars[pic])

        return

    def _cell_renderer_message(self, column, cell, store, position):
        """Callback for the message column. We need this to adjust the markup
        property of the cell, as setting it as text won't do any markup
        processing."""

        data = store.get_value(position, 0)

        message = data.message
        username = data.username

        time = timesince.timesince(data.message_time)

        # unescape escaped entities that pango is not okay with
        message = re.sub(r'&', r'&amp;', message)
        #_log.debug('Rendering message: %s', message)

        # highlight URLs
        mask = r'<span foreground="%s">\1</span>' % (
                self._options[self.NAMESPACE]['link_colour'])
        message = URL_RE.sub(mask, message)

        # use a different highlight for the current user
        # TODO: How to handle this with several networks?
        #message = re.sub(r'(@'+self.twitter.username+')',
        #        r'<span foreground="#FF6633">\1</span>',
        #        message)

        markup = '<b>%s</b> <small>(%s)</small>:\n%s\n<small>%s</small>' % \
                (data.name, username, message, time)
        cell.set_property('markup', markup)

        return

    def _cell_renderer_options(self, column, cell, store, position):
        """Callback for the options renderer. Adds the delete icon if the
        message belongs to the user or reply if not."""
        data = store.get_value(position, 0)
        cell.set_property('pixbuf', self._reply_pixbuf)
        return

    # ------------------------------------------------------------
    # Helper functions
    # ------------------------------------------------------------
    def _update_sensitivity(self, enabled):
        """Set the "sensitive" property of the update action and button. Both
        should have the same property, so whenever you need to disable/enable
        them, use this function."""

        self._update_button.set_property('sensitive', enabled)
        self._update_action.set_property('sensitive', enabled)
        self._cancel_button.set_property('sensitive', enabled)
        self._cancel_action.set_property('sensitive', enabled)
        return
        
    def _update_statusbar(self, message):
        """Update the statusbar with the message."""
        self._statusbar.push(self._statusbar_context, message)
        return

    def _refresh(self, widget=None):
        """Request a refresh. *widget* is the widget that called this
        function (we basically ignore it.)"""
        if self._refresh_id:
            # "De-queue" the next refresh
            _log.debug('Dequeuing next refresh')
            gobject.source_remove(self._refresh_id)
            self._refresh_id = None
            
        # do the refresh
        self._update_statusbar('Retrieving messages...')
        self._threads.add_work(self._post_get_messages,
                self._exception_get_messages,
                self._connection.messages)
                
        # queue the next auto-refresh
        interval = self._options[self.NAMESPACE]['refresh_interval']
        _log.debug('Queueing next refresh in %d minutes', interval)
        self._refresh_id = gobject.timeout_add(
                interval * 60 * 1000,
                self._refresh, None)
        return

    # ------------------------------------------------------------
    # Widget callback functions
    # ------------------------------------------------------------
    def _count_chars(self, text_buffer):
        """Count the number of chars in the edit field and update the
        label that shows the available space."""
        text = _buffer_text(text_buffer)
        count = len(text)

        # TODO: gettext to properly use "characters"/"character"
        self._count_label.set_text('%d characters' % count)
        self._update_sensitivity(not (count == 0))

        return True

    def _update_status(self, widget):
        """Update your status."""
        _log.debug('Updating status.')
        status = _buffer_text(self._update_text.get_buffer())
        status = status.strip()
        if not status:
            return

        _log.debug('Status: %s', status)
        self._update_statusbar('Sending update...')
        self._update_sensitivity(False)
        self._threads.add_work(self._post_update_status,
                self._exception_update_status,
                self._connection.update,
                status)
        # TODO: We are not dealing with replies here yet
        return
        
    def _clear_text(self, widget):
        """Clear the text field."""
        self._update_text.get_buffer().set_text('')
        return

    def _quit_app(self, widget=None, user_data=None):
        """Callback when the window is destroyed or the user selects
        "Quit"."""

        (x, y) = self._main_window.get_position()
        _log.debug('Current position: %d x %d', x, y)
        self._options[self.NAMESPACE]['position_x'] = x
        self._options[self.NAMESPACE]['position_y'] = y

        (width, height) = self._main_window.get_size()
        _log.debug('Current window size: %d x %d', width, height)
        self._options[self.NAMESPACE]['width'] = width
        self._options[self.NAMESPACE]['height'] = height

        gtk.main_quit()
        return

    def _grid_resize(self,  widget, requisition, data=None):
        """Called when the window is resized. We use it to set the proper
        word-wrapping in the message column."""

        model = self._grid.get_model()
        if len(model) == 0:
            # nothing in the list, so we don't have what to set proper word
            # wrapping
            return

        (win_width, win_height) = self._main_window.get_size()
        #_log.debug('Widget size: %d', win_width)

        column = self._grid.get_column(1)
        iter = model.get_iter_first()
        path = model.get_path(iter)

        cell_rectangle = self._grid.get_cell_area(path, column)
        width = win_width - 70  # 48 = icon size
        # TODO: Find out where those 12 pixels came from and/or if they
        # are platform specific.

        for renderer in column.get_cell_renderers():
            renderer.set_property('wrap-width', width)

        while iter:
            path = model.get_path(iter)
            model.row_changed(path, iter)
            iter = model.iter_next(iter)

        return

    def _order_datetime(self, model, iter1, iter2, user_data=None):
        """Used by the ListStore to sort the columns (in our case, "column")
        by date."""
        message1 = model.get_value(iter1, 0)
        message2 = model.get_value(iter2, 0)

        if (not message1) or \
                (not message1.message_time) or \
                (message1.message_time > message2.message_time):
            return -1

        if (not message2) or \
                (not message2.message_time) or \
                (message2.message_time > message1.message_time):
            return 1
        return 0
        
    def _message_selected(self, view, user_data=None):
        """Callback when a row in the list is selected. Mostly, we'll check
        if the message is from the logged user and we change de "sensitive"
        property of the message actions to reflect what the user can and 
        cannot do."""
        
        (model, iter) = view.get_selection().get_selected()
        data = model.get_value(iter, 0)
        
        self._delete_action.set_property('sensitive', 
                self._connection.can_delete(data))
        self._reply_action.set_property('sensitive', 
                self._connection.can_reply(data))
        self._repost_action.set_property('sensitive', 
                self._connection.can_repost(data))
        
        return 0
        
    def _clear_posts(self, widget, user_data=None):
        """Clear the list of posts from the grid."""
        self._grid.get_model().clear()
        return
        
    def _delete_message(self, widget, user_data=None):
        """Delete a message."""
        (model, iter) = self._grid.get_selection().get_selected()
        message = model.get_value(iter, 0)
        
        if not self._connection.can_delete(message):
            # Since we delete only one message, we don't need to worry about
            # multiple networks here.
            error_dialog = gtk.MessageDialog(parent=self._main_window,
                    type=gtk.MESSAGE_ERROR,
                    message_format='Message cannot be deleted',
                    buttons=gtk.BUTTONS_OK)
            error_dialog.run()
            error_dialog.destroy()
            return
        
        self._update_statusbar('Deleting message...')
        self._delete_iter = iter
        _log.debug('Deleting messing %d', message.id)
        self._threads.add_work(self._post_delete_message,
                self._exception_delete_message,
                self._connection.delete_message,
                message)
        return

    # ------------------------------------------------------------
    # Network related functions
    # ------------------------------------------------------------
    
    ### Results from the "messages" request
    def _post_get_messages(self, widget, results):
        """Function called after the data from the messages list is
        retrieved."""
        _log.debug('%d new tweets', len(results))
        interval = self._options[self.NAMESPACE]['refresh_interval']
        self._update_statusbar('Messages retrieved. Next update in ' \
                '%d minutes.' % interval)

        store = self._grid.get_model()
        for message in results:
            _log.debug('Data: %s', str(message))
            store.prepend([message])
        store.sort_column_changed()
        self._grid.queue_draw()
        return

    def _exception_get_messages(self, widget, exception):
        """Function called if the retrival of current messages returns an
        exception."""
        _log.debug(str(exception))
        return

    ### image download function
    def _download_pic(self, url):
        """Download a picture from the web. Can be used in a thread."""
        request = urllib2.Request(url=url)
        _log.debug('Starting request of %s' % (url))
        response = urllib2.urlopen(request)
        data = response.read()
        _log.debug('Request completed')

        return (url, data)

    ### Results from the picture request
    def _post_download_pic(self, widget, data):
        """Called after the data from the picture is available."""

        (url, data) = data

        loader = gtk.gdk.PixbufLoader()
        loader.write(data)
        loader.close()

        user_pic = loader.get_pixbuf()
        user_pic = user_pic.scale_simple(48, 48, gtk.gdk.INTERP_BILINEAR)
        self._avatars[url] = user_pic

        self._grid.queue_draw()
        return

    def _exception_download_pic(self, widget, exception):
        """Called in case we have a problem downloading an user avatar."""
        _log.debug('Exception trying to get an avatar.')
        _log.debug(str(exception))
        return

    ### Results for the update status call
    def _post_update_status(self, widget, data):
        """Called when the status is updated correctly."""
        self._update_sensitivity(True)
        self._clear_text(None)
        self._update_statusbar('Your status was updated.')
        return

    def _exception_update_status(self, widget, exception):
        """Called when there is an exception updating the status."""
        # TODO: Need the check the type of exception we got.
        _log.debug('Update error')
        _log.debug(str(exception))
        return
        
    ### Results for the delete message call
    def _post_delete_message(self, widget, data):
        """Called when the message is deleted successfully."""
        _log.debug('Message deleted.')
        if self._delete_iter:
            self._grid.get_model().remove(self._delete_iter)
            self._delete_iter = None
        self._update_statusbar('Message deleted.')
        return
        
    def _exception_delete_message(self, widget, exception):
        """Called when the message cannot be deleted."""
        _log.debug('Delete error')
        _log.debug(str(exception))
        return

    # ------------------------------------------------------------
    # Required functions for all interfaces
    # ------------------------------------------------------------
    def __init__(self, connection, options):
        """Start the interface. `connection` is the :class:`Networks` object
        with all the available networks. `options` is the :class:`ConfigOpt`
        object with the configuration to run Mitter."""

        self._connection = connection
        self._options = options

        self._avatars = {}
        self._pic_queue = set()

        # Load images
        self._app_icon = find_image('mitter.png')
        self._app_icon_alert = find_image('mitter-new.png')
        self._reply_pixbuf = gtk.gdk.pixbuf_new_from_file(
                find_image('reply.png'))
        #self._delete_icon = find_image('icon_trash.gif')

        unknown_pixbuf = find_image('unknown.png')
        if unknown_pixbuf:
            self._default_pixmap = gtk.gdk.pixbuf_new_from_file(
                    unknown_pixbuf)
        else:
            self._default_pixmap = gtk.gdk.Pixbuf(gtk.gdk.COLORSPACE_RGB,
                    has_alpha=False, bits_per_sample=8, width=48, height=48)

        # This is the ugly bit for speeding up things and making
        # interthread communication.
        self._delete_iter = None
        self._reply_message = None
        self._repost_message = None
        
        return
        
    def __call__(self):
        """Call function; displays the interface. This method should appear on
        every interface."""

        self._main_window = self._create_main_window()
        self._main_window.show_all()
        self._threads = _ThreadManager()

        # queue the first fetch
        self._refresh_id = None     # The auto-refresh manager.
        self._refresh()
        gtk.main()

    @classmethod
    def options(self, options):
        """Add the options for this interface."""
        options.add_group(self.NAMESPACE, 'GTK+ Interface')
        options.add_option('--refresh-interval',
                group=self.NAMESPACE,
                option='refresh_interval',
                help='Refresh interval',
                type='int',
                metavar='MINUTES',
                default=5,
                conflict_group='interface')
        # Most of the options for non-cmd-options are useless, but I'm keeping
        # them as documentation.
        options.add_option(
                group=self.NAMESPACE,
                option='width',
                help='Window width',
                type='int',
                metavar='PIXELS',
                default=450,
                conflict_group='interface',
                is_cmd_option=False)
        options.add_option(
                group=self.NAMESPACE,
                option='height',
                help='Window height',
                type='int',
                metavar='PIXELS',
                default=300,
                conflict_group='interface',
                is_cmd_option=False)
        options.add_option(
                group=self.NAMESPACE,
                option='position_x',
                help='Window position on the X axis',
                type='int',
                metavar='PIXELS',
                default=5,
                conflict_group='interface',
                is_cmd_option=False)
        options.add_option(
                group=self.NAMESPACE,
                option='position_y',
                help='Window position on the Y axis',
                type='int',
                metavar='PIXELS',
                default=5,
                conflict_group='interface',
                is_cmd_option=False)
        options.add_option(
                group=self.NAMESPACE,
                option='max_status_display',
                help='Maximum number of elements to keep internally',
                type='int',
                metavar='MESSAGES',
                default=60,
                conflict_group='interface',
                is_cmd_option=False)        # TODO: Should it be config only?
        options.add_option(
                group=self.NAMESPACE,
                option='link_colour',
                help='Color of links in the interface',
                type='str',
                metavar='COLOR',
                default='blue',
                conflict_group='interface',
                is_cmd_option=False)
        options.add_option(
                group=self.NAMESPACE,
                option='spell_check',
                help='Spell checking update text',
                type='boolean',
                metavar='SPELL',
                default=False,
                conflict_group='interface',
                is_cmd_option=False)