refactor buffers

This splits buffers.py, which contained all buffer classes, into several smaller files.
issue #1226

9 files changed, 747 insertions, 701 deletions

diff --git a/alot/buffers.py b/alot/buffers.py
deleted file mode 100644
index 4f0a7044..00000000
--- a/alot/buffers.py
+++ /dev/null
@@ -1,700 +0,0 @@
-# Copyright (C) 2011-2012  Patrick Totzke <patricktotzke@gmail.com>
-# This file is released under the GNU GPL, version 3 or a later revision.
-# For further details see the COPYING file
-import logging
-import os
-
-import urwid
-from urwidtrees import ArrowTree, TreeBox, NestedTree
-from notmuch import NotmuchError
-
-from .settings.const import settings
-from . import commands
-from .walker import PipeWalker
-from .helper import shorten_author_string
-from .db.errors import NonexistantObjectError
-from .widgets.globals import TagWidget
-from .widgets.globals import HeadersList
-from .widgets.globals import AttachmentWidget
-from .widgets.bufferlist import BufferlineWidget
-from .widgets.search import ThreadlineWidget
-from .widgets.thread import ThreadTree
-
-
-class Buffer(object):
-    """Abstract base class for buffers."""
-
-    modename = None  # mode identifier for subclasses
-
-    def __init__(self, ui, widget):
-        self.ui = ui
-        self.body = widget
-
-    def __str__(self):
-        return '[%s]' % self.modename
-
-    def render(self, size, focus=False):
-        return self.body.render(size, focus)
-
-    def selectable(self):
-        return self.body.selectable()
-
-    def rebuild(self):
-        """tells the buffer to (re)construct its visible content."""
-        pass
-
-    def keypress(self, size, key):
-        return self.body.keypress(size, key)
-
-    def cleanup(self):
-        """called before buffer is closed"""
-        pass
-
-    def get_info(self):
-        """
-        return dict of meta infos about this buffer.
-        This can be requested to be displayed in the statusbar.
-        """
-        return {}
-
-
-class BufferlistBuffer(Buffer):
-    """lists all active buffers"""
-
-    modename = 'bufferlist'
-
-    def __init__(self, ui, filtfun=lambda x: x):
-        self.filtfun = filtfun
-        self.ui = ui
-        self.isinitialized = False
-        self.rebuild()
-        Buffer.__init__(self, ui, self.body)
-
-    def index_of(self, b):
-        """
-        returns the index of :class:`Buffer` `b` in the global list of active
-        buffers.
-        """
-        return self.ui.buffers.index(b)
-
-    def rebuild(self):
-        if self.isinitialized:
-            focusposition = self.bufferlist.get_focus()[1]
-        else:
-            focusposition = 0
-            self.isinitialized = True
-
-        lines = list()
-        displayedbuffers = [b for b in self.ui.buffers if self.filtfun(b)]
-        for (num, b) in enumerate(displayedbuffers):
-            line = BufferlineWidget(b)
-            if (num % 2) == 0:
-                attr = settings.get_theming_attribute('bufferlist',
-                                                      'line_even')
-            else:
-                attr = settings.get_theming_attribute('bufferlist', 'line_odd')
-            focus_att = settings.get_theming_attribute('bufferlist',
-                                                       'line_focus')
-            buf = urwid.AttrMap(line, attr, focus_att)
-            num = urwid.Text('%3d:' % self.index_of(b))
-            lines.append(urwid.Columns([('fixed', 4, num), buf]))
-        self.bufferlist = urwid.ListBox(urwid.SimpleListWalker(lines))
-        num_buffers = len(displayedbuffers)
-        if focusposition is not None and num_buffers > 0:
-            self.bufferlist.set_focus(focusposition % num_buffers)
-        self.body = self.bufferlist
-
-    def get_selected_buffer(self):
-        """returns currently selected :class:`Buffer` element from list"""
-        linewidget, _ = self.bufferlist.get_focus()
-        bufferlinewidget = linewidget.get_focus().original_widget
-        return bufferlinewidget.get_buffer()
-
-    def focus_first(self):
-        """Focus the first line in the buffer list."""
-        self.body.set_focus(0)
-
-
-class EnvelopeBuffer(Buffer):
-    """message composition mode"""
-
-    modename = 'envelope'
-
-    def __init__(self, ui, envelope):
-        self.ui = ui
-        self.envelope = envelope
-        self.all_headers = False
-        self.rebuild()
-        Buffer.__init__(self, ui, self.body)
-
-    def __str__(self):
-        to = self.envelope.get('To', fallback='unset')
-        return '[envelope] to: %s' % (shorten_author_string(to, 400))
-
-    def get_info(self):
-        info = {}
-        info['to'] = self.envelope.get('To', fallback='unset')
-        return info
-
-    def cleanup(self):
-        if self.envelope.tmpfile:
-            os.unlink(self.envelope.tmpfile.name)
-
-    def rebuild(self):
-        displayed_widgets = []
-        hidden = settings.get('envelope_headers_blacklist')
-        # build lines
-        lines = []
-        for (k, vlist) in self.envelope.headers.items():
-            if (k not in hidden) or self.all_headers:
-                for value in vlist:
-                    lines.append((k, value))
-
-        # sign/encrypt lines
-        if self.envelope.sign:
-            description = 'Yes'
-            sign_key = self.envelope.sign_key
-            if sign_key is not None and len(sign_key.subkeys) > 0:
-                description += ', with key ' + sign_key.uids[0].uid
-            lines.append(('GPG sign', description))
-
-        if self.envelope.encrypt:
-            description = 'Yes'
-            encrypt_keys = self.envelope.encrypt_keys.values()
-            if len(encrypt_keys) == 1:
-                description += ', with key '
-            elif len(encrypt_keys) > 1:
-                description += ', with keys '
-            key_ids = []
-            for key in encrypt_keys:
-                if key is not None and key.subkeys:
-                    key_ids.append(key.uids[0].uid)
-            description += ', '.join(key_ids)
-            lines.append(('GPG encrypt', description))
-
-        if self.envelope.tags:
-            lines.append(('Tags', ','.join(self.envelope.tags)))
-
-        # add header list widget iff header values exists
-        if lines:
-            key_att = settings.get_theming_attribute('envelope', 'header_key')
-            value_att = settings.get_theming_attribute('envelope',
-                                                       'header_value')
-            gaps_att = settings.get_theming_attribute('envelope', 'header')
-            self.header_wgt = HeadersList(lines, key_att, value_att, gaps_att)
-            displayed_widgets.append(self.header_wgt)
-
-        # display attachments
-        lines = []
-        for a in self.envelope.attachments:
-            lines.append(AttachmentWidget(a, selectable=False))
-        if lines:
-            self.attachment_wgt = urwid.Pile(lines)
-            displayed_widgets.append(self.attachment_wgt)
-
-        self.body_wgt = urwid.Text(self.envelope.body)
-        displayed_widgets.append(self.body_wgt)
-        self.body = urwid.ListBox(displayed_widgets)
-
-    def toggle_all_headers(self):
-        """toggles visibility of all envelope headers"""
-        self.all_headers = not self.all_headers
-        self.rebuild()
-
-
-class SearchBuffer(Buffer):
-    """shows a result list of threads for a query"""
-
-    modename = 'search'
-    threads = []
-    _REVERSE = {'oldest_first': 'newest_first',
-                'newest_first': 'oldest_first'}
-
-    def __init__(self, ui, initialquery='', sort_order=None):
-        self.dbman = ui.dbman
-        self.ui = ui
-        self.querystring = initialquery
-        default_order = settings.get('search_threads_sort_order')
-        self.sort_order = sort_order or default_order
-        self.result_count = 0
-        self.isinitialized = False
-        self.proc = None  # process that fills our pipe
-        self.rebuild()
-        Buffer.__init__(self, ui, self.body)
-
-    def __str__(self):
-        formatstring = '[search] for "%s" (%d message%s)'
-        return formatstring % (self.querystring, self.result_count,
-                               's' if self.result_count > 1 else '')
-
-    def get_info(self):
-        info = {}
-        info['querystring'] = self.querystring
-        info['result_count'] = self.result_count
-        info['result_count_positive'] = 's' if self.result_count > 1 else ''
-        return info
-
-    def cleanup(self):
-        self.kill_filler_process()
-
-    def kill_filler_process(self):
-        """
-        terminates the process that fills this buffers
-        :class:`~alot.walker.PipeWalker`.
-        """
-        if self.proc:
-            if self.proc.is_alive():
-                self.proc.terminate()
-
-    def rebuild(self, reverse=False):
-        self.isinitialized = True
-        self.reversed = reverse
-        self.kill_filler_process()
-
-        if reverse:
-            order = self._REVERSE[self.sort_order]
-        else:
-            order = self.sort_order
-
-        exclude_tags = settings.get_notmuch_setting('search', 'exclude_tags')
-        if exclude_tags:
-            exclude_tags = [t for t in exclude_tags.split(';') if t]
-
-        try:
-            self.result_count = self.dbman.count_messages(self.querystring)
-            self.pipe, self.proc = self.dbman.get_threads(self.querystring,
-                                                          order,
-                                                          exclude_tags)
-        except NotmuchError:
-            self.ui.notify('malformed query string: %s' % self.querystring,
-                           'error')
-            self.listbox = urwid.ListBox([])
-            self.body = self.listbox
-            return
-
-        self.threadlist = PipeWalker(self.pipe, ThreadlineWidget,
-                                     dbman=self.dbman,
-                                     reverse=reverse)
-
-        self.listbox = urwid.ListBox(self.threadlist)
-        self.body = self.listbox
-
-    def get_selected_threadline(self):
-        """
-        returns curently focussed :class:`alot.widgets.ThreadlineWidget`
-        from the result list.
-        """
-        threadlinewidget, _ = self.threadlist.get_focus()
-        return threadlinewidget
-
-    def get_selected_thread(self):
-        """returns currently selected :class:`~alot.db.Thread`"""
-        threadlinewidget = self.get_selected_threadline()
-        thread = None
-        if threadlinewidget:
-            thread = threadlinewidget.get_thread()
-        return thread
-
-    def consume_pipe(self):
-        while not self.threadlist.empty:
-            self.threadlist._get_next_item()
-
-    def focus_first(self):
-        if not self.reversed:
-            self.body.set_focus(0)
-        else:
-            self.rebuild(reverse=False)
-
-    def focus_last(self):
-        if self.reversed:
-            self.body.set_focus(0)
-        elif self.result_count < 200 or self.sort_order not in self._REVERSE:
-            self.consume_pipe()
-            num_lines = len(self.threadlist.get_lines())
-            self.body.set_focus(num_lines - 1)
-        else:
-            self.rebuild(reverse=True)
-
-
-class ThreadBuffer(Buffer):
-    """displays a thread as a tree of messages"""
-
-    modename = 'thread'
-
-    def __init__(self, ui, thread):
-        """
-        :param ui: main UI
-        :type ui: :class:`~alot.ui.UI`
-        :param thread: thread to display
-        :type thread: :class:`~alot.db.Thread`
-        """
-        self.thread = thread
-        self.message_count = thread.get_total_messages()
-
-        # two semaphores for auto-removal of unread tag
-        self._auto_unread_dont_touch_mids = set([])
-        self._auto_unread_writing = False
-
-        self._indent_width = settings.get('thread_indent_replies')
-        self.rebuild()
-        Buffer.__init__(self, ui, self.body)
-
-    def __str__(self):
-        return '[thread] %s (%d message%s)' % (self.thread.get_subject(),
-                                               self.message_count,
-                                               's' * (self.message_count > 1))
-
-    def get_info(self):
-        info = {}
-        info['subject'] = self.thread.get_subject()
-        info['authors'] = self.thread.get_authors_string()
-        info['tid'] = self.thread.get_thread_id()
-        info['message_count'] = self.message_count
-        return info
-
-    def get_selected_thread(self):
-        """returns the displayed :class:`~alot.db.Thread`"""
-        return self.thread
-
-    def rebuild(self):
-        try:
-            self.thread.refresh()
-        except NonexistantObjectError:
-            self.body = urwid.SolidFill()
-            self.message_count = 0
-            return
-
-        self._tree = ThreadTree(self.thread)
-
-        # define A to be the tree to be wrapped by a NestedTree and displayed.
-        # We wrap the thread tree into an ArrowTree for decoration if
-        # indentation was requested and otherwise use it as is.
-        if self._indent_width == 0:
-            A = self._tree
-        else:
-            # we want decoration.
-            bars_att = settings.get_theming_attribute('thread', 'arrow_bars')
-            # only add arrow heads if there is space (indent > 1).
-            heads_char = None
-            heads_att = None
-            if self._indent_width > 1:
-                heads_char = u'\u27a4'
-                heads_att = settings.get_theming_attribute('thread',
-                                                           'arrow_heads')
-            A = ArrowTree(
-                self._tree,
-                indent=self._indent_width,
-                childbar_offset=0,
-                arrow_tip_att=heads_att,
-                arrow_tip_char=heads_char,
-                arrow_att=bars_att)
-
-        self._nested_tree = NestedTree(A, interpret_covered=True)
-        self.body = TreeBox(self._nested_tree)
-        self.message_count = self.thread.get_total_messages()
-
-    def render(self, size, focus=False):
-        if self.message_count == 0:
-            return self.body.render(size, focus)
-
-        if settings.get('auto_remove_unread'):
-            logging.debug('Tbuffer: auto remove unread tag from msg?')
-            msg = self.get_selected_message()
-            mid = msg.get_message_id()
-            focus_pos = self.body.get_focus()[1]
-            summary_pos = (self.body.get_focus()[1][0], (0,))
-            cursor_on_non_summary = (focus_pos != summary_pos)
-            if cursor_on_non_summary:
-                if mid not in self._auto_unread_dont_touch_mids:
-                    if 'unread' in msg.get_tags():
-                        logging.debug('Tbuffer: removing unread')
-
-                        def clear():
-                            self._auto_unread_writing = False
-
-                        self._auto_unread_dont_touch_mids.add(mid)
-                        self._auto_unread_writing = True
-                        msg.remove_tags(['unread'], afterwards=clear)
-                        fcmd = commands.globals.FlushCommand(silent=True)
-                        self.ui.apply_command(fcmd)
-                    else:
-                        logging.debug('Tbuffer: No, msg not unread')
-                else:
-                    logging.debug('Tbuffer: No, mid locked for autorm-unread')
-            else:
-                if not self._auto_unread_writing and \
-                   mid in self._auto_unread_dont_touch_mids:
-                    self._auto_unread_dont_touch_mids.remove(mid)
-                logging.debug('Tbuffer: No, cursor on summary')
-        return self.body.render(size, focus)
-
-    def get_selected_mid(self):
-        """returns Message ID of focussed message"""
-        return self.body.get_focus()[1][0]
-
-    def get_selected_message_position(self):
-        """returns position of focussed message in the thread tree"""
-        return self._sanitize_position((self.get_selected_mid(),))
-
-    def get_selected_messagetree(self):
-        """returns currently focussed :class:`MessageTree`"""
-        return self._nested_tree[self.body.get_focus()[1][:1]]
-
-    def get_selected_message(self):
-        """returns focussed :class:`~alot.db.message.Message`"""
-        return self.get_selected_messagetree()._message
-
-    def get_messagetree_positions(self):
-        """
-        returns a Generator to walk through all positions of
-        :class:`MessageTree` in the :class:`ThreadTree` of this buffer.
-        """
-        return [(pos,) for pos in self._tree.positions()]
-
-    def messagetrees(self):
-        """
-        returns a Generator of all :class:`MessageTree` in the
-        :class:`ThreadTree` of this buffer.
-        """
-        for pos in self._tree.positions():
-            yield self._tree[pos]
-
-    def refresh(self):
-        """refresh and flushe caches of Thread tree"""
-        self.body.refresh()
-
-    # needed for ui.get_deep_focus..
-    def get_focus(self):
-        "Get the focus from the underlying body widget."
-        return self.body.get_focus()
-
-    def set_focus(self, pos):
-        "Set the focus in the underlying body widget."
-        logging.debug('setting focus to %s ', pos)
-        self.body.set_focus(pos)
-
-    def focus_first(self):
-        """set focus to first message of thread"""
-        self.body.set_focus(self._nested_tree.root)
-
-    def focus_last(self):
-        self.body.set_focus(next(self._nested_tree.positions(reverse=True)))
-
-    def _sanitize_position(self, pos):
-        return self._nested_tree._sanitize_position(pos,
-                                                    self._nested_tree._tree)
-
-    def focus_selected_message(self):
-        """focus the summary line of currently focussed message"""
-        # move focus to summary (root of current MessageTree)
-        self.set_focus(self.get_selected_message_position())
-
-    def focus_parent(self):
-        """move focus to parent of currently focussed message"""
-        mid = self.get_selected_mid()
-        newpos = self._tree.parent_position(mid)
-        if newpos is not None:
-            newpos = self._sanitize_position((newpos,))
-            self.body.set_focus(newpos)
-
-    def focus_first_reply(self):
-        """move focus to first reply to currently focussed message"""
-        mid = self.get_selected_mid()
-        newpos = self._tree.first_child_position(mid)
-        if newpos is not None:
-            newpos = self._sanitize_position((newpos,))
-            self.body.set_focus(newpos)
-
-    def focus_last_reply(self):
-        """move focus to last reply to currently focussed message"""
-        mid = self.get_selected_mid()
-        newpos = self._tree.last_child_position(mid)
-        if newpos is not None:
-            newpos = self._sanitize_position((newpos,))
-            self.body.set_focus(newpos)
-
-    def focus_next_sibling(self):
-        """focus next sibling of currently focussed message in thread tree"""
-        mid = self.get_selected_mid()
-        newpos = self._tree.next_sibling_position(mid)
-        if newpos is not None:
-            newpos = self._sanitize_position((newpos,))
-            self.body.set_focus(newpos)
-
-    def focus_prev_sibling(self):
-        """
-        focus previous sibling of currently focussed message in thread tree
-        """
-        mid = self.get_selected_mid()
-        localroot = self._sanitize_position((mid,))
-        if localroot == self.get_focus()[1]:
-            newpos = self._tree.prev_sibling_position(mid)
-            if newpos is not None:
-                newpos = self._sanitize_position((newpos,))
-        else:
-            newpos = localroot
-        if newpos is not None:
-            self.body.set_focus(newpos)
-
-    def focus_next(self):
-        """focus next message in depth first order"""
-        mid = self.get_selected_mid()
-        newpos = self._tree.next_position(mid)
-        if newpos is not None:
-            newpos = self._sanitize_position((newpos,))
-            self.body.set_focus(newpos)
-
-    def focus_prev(self):
-        """focus previous message in depth first order"""
-        mid = self.get_selected_mid()
-        localroot = self._sanitize_position((mid,))
-        if localroot == self.get_focus()[1]:
-            newpos = self._tree.prev_position(mid)
-            if newpos is not None:
-                newpos = self._sanitize_position((newpos,))
-        else:
-            newpos = localroot
-        if newpos is not None:
-            self.body.set_focus(newpos)
-
-    def focus_property(self, prop, direction):
-        """does a walk in the given direction and focuses the
-        first message tree that matches the given property"""
-        newpos = self.get_selected_mid()
-        newpos = direction(newpos)
-        while newpos is not None:
-            MT = self._tree[newpos]
-            if prop(MT):
-                newpos = self._sanitize_position((newpos,))
-                self.body.set_focus(newpos)
-                break
-            newpos = direction(newpos)
-
-    def focus_next_matching(self, querystring):
-        """focus next matching message in depth first order"""
-        self.focus_property(lambda x: x._message.matches(querystring),
-                            self._tree.next_position)
-
-    def focus_prev_matching(self, querystring):
-        """focus previous matching message in depth first order"""
-        self.focus_property(lambda x: x._message.matches(querystring),
-                            self._tree.prev_position)
-
-    def focus_next_unfolded(self):
-        """focus next unfolded message in depth first order"""
-        self.focus_property(lambda x: not x.is_collapsed(x.root),
-                            self._tree.next_position)
-
-    def focus_prev_unfolded(self):
-        """focus previous unfolded message in depth first order"""
-        self.focus_property(lambda x: not x.is_collapsed(x.root),
-                            self._tree.prev_position)
-
-    def expand(self, msgpos):
-        """expand message at given position"""
-        MT = self._tree[msgpos]
-        MT.expand(MT.root)
-
-    def messagetree_at_position(self, pos):
-        """get :class:`MessageTree` for given position"""
-        return self._tree[pos[0]]
-
-    def expand_all(self):
-        """expand all messages in thread"""
-        for MT in self.messagetrees():
-            MT.expand(MT.root)
-
-    def collapse(self, msgpos):
-        """collapse message at given position"""
-        MT = self._tree[msgpos]
-        MT.collapse(MT.root)
-        self.focus_selected_message()
-
-    def collapse_all(self):
-        """collapse all messages in thread"""
-        for MT in self.messagetrees():
-            MT.collapse(MT.root)
-        self.focus_selected_message()
-
-    def unfold_matching(self, querystring, focus_first=True):
-        """
-        expand all messages that match a given querystring.
-
-        :param querystring: query to match
-        :type querystring: str
-        :param focus_first: set the focus to the first matching message
-        :type focus_first: bool
-        """
-        first = None
-        for MT in self.messagetrees():
-            msg = MT._message
-            if msg.matches(querystring):
-                MT.expand(MT.root)
-                if first is None:
-                    first = (self._tree.position_of_messagetree(MT), MT.root)
-                    self.body.set_focus(first)
-            else:
-                MT.collapse(MT.root)
-        self.body.refresh()
-
-
-class TagListBuffer(Buffer):
-    """lists all tagstrings present in the notmuch database"""
-
-    modename = 'taglist'
-
-    def __init__(self, ui, alltags=None, filtfun=lambda x: x):
-        self.filtfun = filtfun
-        self.ui = ui
-        self.tags = alltags or []
-        self.isinitialized = False
-        self.rebuild()
-        Buffer.__init__(self, ui, self.body)
-
-    def rebuild(self):
-        if self.isinitialized:
-            focusposition = self.taglist.get_focus()[1]
-        else:
-            focusposition = 0
-            self.isinitialized = True
-
-        lines = list()
-        displayedtags = sorted((t for t in self.tags if self.filtfun(t)),
-                               key=str.lower)
-        for (num, b) in enumerate(displayedtags):
-            if (num % 2) == 0:
-                attr = settings.get_theming_attribute('taglist', 'line_even')
-            else:
-                attr = settings.get_theming_attribute('taglist', 'line_odd')
-            focus_att = settings.get_theming_attribute('taglist', 'line_focus')
-
-            tw = TagWidget(b, attr, focus_att)
-            rows = [('fixed', tw.width(), tw)]
-            if tw.hidden:
-                rows.append(urwid.Text(b + ' [hidden]'))
-            elif tw.translated is not b:
-                rows.append(urwid.Text('(%s)' % b))
-            line = urwid.Columns(rows, dividechars=1)
-            line = urwid.AttrMap(line, attr, focus_att)
-            lines.append(line)
-
-        self.taglist = urwid.ListBox(urwid.SimpleListWalker(lines))
-        self.body = self.taglist
-
-        self.taglist.set_focus(focusposition % len(displayedtags))
-
-    def focus_first(self):
-        """Focus the first line in the tag list."""
-        self.body.set_focus(0)
-
-    def focus_last(self):
-        allpos = self.taglist.body.positions(reverse=True)
-        if allpos:
-            lastpos = allpos[0]
-            self.body.set_focus(lastpos)
-
-    def get_selected_tag(self):
-        """returns selected tagstring"""
-        cols, _ = self.taglist.get_focus()
-        tagwidget = cols.original_widget.get_focus()
-        return tagwidget.tag
diff --git a/alot/buffers/__init__.py b/alot/buffers/__init__.py
new file mode 100644
index 00000000..2b52a544
--- /dev/null
+++ b/alot/buffers/__init__.py
@@ -0,0 +1,10 @@
+# Copyright (C) 2011-2018  Patrick Totzke <patricktotzke@gmail.com>
+# This file is released under the GNU GPL, version 3 or a later revision.
+# For further details see the COPYING file
+
+from .buffer import Buffer
+from .bufferlist import BufferlistBuffer
+from .envelope import EnvelopeBuffer
+from .search import SearchBuffer
+from .taglist import TagListBuffer
+from .thread import ThreadBuffer
diff --git a/alot/buffers/buffer.py b/alot/buffers/buffer.py
new file mode 100644
index 00000000..fc0e7af7
--- /dev/null
+++ b/alot/buffers/buffer.py
@@ -0,0 +1,40 @@
+# Copyright (C) 2011-2018  Patrick Totzke <patricktotzke@gmail.com>
+# This file is released under the GNU GPL, version 3 or a later revision.
+# For further details see the COPYING file
+
+
+class Buffer(object):
+    """Abstract base class for buffers."""
+
+    modename = None  # mode identifier for subclasses
+
+    def __init__(self, ui, widget):
+        self.ui = ui
+        self.body = widget
+
+    def __str__(self):
+        return '[%s]' % self.modename
+
+    def render(self, size, focus=False):
+        return self.body.render(size, focus)
+
+    def selectable(self):
+        return self.body.selectable()
+
+    def rebuild(self):
+        """tells the buffer to (re)construct its visible content."""
+        pass
+
+    def keypress(self, size, key):
+        return self.body.keypress(size, key)
+
+    def cleanup(self):
+        """called before buffer is closed"""
+        pass
+
+    def get_info(self):
+        """
+        return dict of meta infos about this buffer.
+        This can be requested to be displayed in the statusbar.
+        """
+        return {}
diff --git a/alot/buffers/bufferlist.py b/alot/buffers/bufferlist.py
new file mode 100644
index 00000000..db6395de
--- /dev/null
+++ b/alot/buffers/bufferlist.py
@@ -0,0 +1,66 @@
+# Copyright (C) 2011-2018  Patrick Totzke <patricktotzke@gmail.com>
+# This file is released under the GNU GPL, version 3 or a later revision.
+# For further details see the COPYING file
+from __future__ import absolute_import
+import urwid
+
+from .buffer import Buffer
+from ..widgets.bufferlist import BufferlineWidget
+from ..settings.const import settings
+
+
+class BufferlistBuffer(Buffer):
+    """lists all active buffers"""
+
+    modename = 'bufferlist'
+
+    def __init__(self, ui, filtfun=lambda x: x):
+        self.filtfun = filtfun
+        self.ui = ui
+        self.isinitialized = False
+        self.rebuild()
+        Buffer.__init__(self, ui, self.body)
+
+    def index_of(self, b):
+        """
+        returns the index of :class:`Buffer` `b` in the global list of active
+        buffers.
+        """
+        return self.ui.buffers.index(b)
+
+    def rebuild(self):
+        if self.isinitialized:
+            focusposition = self.bufferlist.get_focus()[1]
+        else:
+            focusposition = 0
+            self.isinitialized = True
+
+        lines = list()
+        displayedbuffers = [b for b in self.ui.buffers if self.filtfun(b)]
+        for (num, b) in enumerate(displayedbuffers):
+            line = BufferlineWidget(b)
+            if (num % 2) == 0:
+                attr = settings.get_theming_attribute('bufferlist',
+                                                      'line_even')
+            else:
+                attr = settings.get_theming_attribute('bufferlist', 'line_odd')
+            focus_att = settings.get_theming_attribute('bufferlist',
+                                                       'line_focus')
+            buf = urwid.AttrMap(line, attr, focus_att)
+            num = urwid.Text('%3d:' % self.index_of(b))
+            lines.append(urwid.Columns([('fixed', 4, num), buf]))
+        self.bufferlist = urwid.ListBox(urwid.SimpleListWalker(lines))
+        num_buffers = len(displayedbuffers)
+        if focusposition is not None and num_buffers > 0:
+            self.bufferlist.set_focus(focusposition % num_buffers)
+        self.body = self.bufferlist
+
+    def get_selected_buffer(self):
+        """returns currently selected :class:`Buffer` element from list"""
+        linewidget, _ = self.bufferlist.get_focus()
+        bufferlinewidget = linewidget.get_focus().original_widget
+        return bufferlinewidget.get_buffer()
+
+    def focus_first(self):
+        """Focus the first line in the buffer list."""
+        self.body.set_focus(0)
diff --git a/alot/buffers/envelope.py b/alot/buffers/envelope.py
new file mode 100644
index 00000000..ef88bed3
--- /dev/null
+++ b/alot/buffers/envelope.py
@@ -0,0 +1,98 @@
+# Copyright (C) 2011-2018  Patrick Totzke <patricktotzke@gmail.com>
+# This file is released under the GNU GPL, version 3 or a later revision.
+# For further details see the COPYING file
+from __future__ import absolute_import
+import urwid
+import os
+
+from .buffer import Buffer
+from ..settings.const import settings
+from ..widgets.globals import HeadersList
+from ..widgets.globals import AttachmentWidget
+
+
+class EnvelopeBuffer(Buffer):
+    """message composition mode"""
+
+    modename = 'envelope'
+
+    def __init__(self, ui, envelope):
+        self.ui = ui
+        self.envelope = envelope
+        self.all_headers = False
+        self.rebuild()
+        Buffer.__init__(self, ui, self.body)
+
+    def __str__(self):
+        to = self.envelope.get('To', fallback='unset')
+        return '[envelope] to: %s' % (shorten_author_string(to, 400))
+
+    def get_info(self):
+        info = {}
+        info['to'] = self.envelope.get('To', fallback='unset')
+        return info
+
+    def cleanup(self):
+        if self.envelope.tmpfile:
+            os.unlink(self.envelope.tmpfile.name)
+
+    def rebuild(self):
+        displayed_widgets = []
+        hidden = settings.get('envelope_headers_blacklist')
+        # build lines
+        lines = []
+        for (k, vlist) in self.envelope.headers.items():
+            if (k not in hidden) or self.all_headers:
+                for value in vlist:
+                    lines.append((k, value))
+
+        # sign/encrypt lines
+        if self.envelope.sign:
+            description = 'Yes'
+            sign_key = self.envelope.sign_key
+            if sign_key is not None and len(sign_key.subkeys) > 0:
+                description += ', with key ' + sign_key.uids[0].uid
+            lines.append(('GPG sign', description))
+
+        if self.envelope.encrypt:
+            description = 'Yes'
+            encrypt_keys = self.envelope.encrypt_keys.values()
+            if len(encrypt_keys) == 1:
+                description += ', with key '
+            elif len(encrypt_keys) > 1:
+                description += ', with keys '
+            key_ids = []
+            for key in encrypt_keys:
+                if key is not None and key.subkeys:
+                    key_ids.append(key.uids[0].uid)
+            description += ', '.join(key_ids)
+            lines.append(('GPG encrypt', description))
+
+        if self.envelope.tags:
+            lines.append(('Tags', ','.join(self.envelope.tags)))
+
+        # add header list widget iff header values exists
+        if lines:
+            key_att = settings.get_theming_attribute('envelope', 'header_key')
+            value_att = settings.get_theming_attribute('envelope',
+                                                       'header_value')
+            gaps_att = settings.get_theming_attribute('envelope', 'header')
+            self.header_wgt = HeadersList(lines, key_att, value_att, gaps_att)
+            displayed_widgets.append(self.header_wgt)
+
+        # display attachments
+        lines = []
+        for a in self.envelope.attachments:
+            lines.append(AttachmentWidget(a, selectable=False))
+        if lines:
+            self.attachment_wgt = urwid.Pile(lines)
+            displayed_widgets.append(self.attachment_wgt)
+
+        self.body_wgt = urwid.Text(self.envelope.body)
+        displayed_widgets.append(self.body_wgt)
+        self.body = urwid.ListBox(displayed_widgets)
+
+    def toggle_all_headers(self):
+        """toggles visibility of all envelope headers"""
+        self.all_headers = not self.all_headers
+        self.rebuild()
diff --git a/alot/buffers/search.py b/alot/buffers/search.py
new file mode 100644
index 00000000..93359d5e
--- /dev/null
+++ b/alot/buffers/search.py
@@ -0,0 +1,125 @@
+# Copyright (C) 2011-2018  Patrick Totzke <patricktotzke@gmail.com>
+# This file is released under the GNU GPL, version 3 or a later revision.
+# For further details see the COPYING file
+from __future__ import absolute_import
+import urwid
+
+from .buffer import Buffer
+from ..settings.const import settings
+from ..walker import PipeWalker
+from ..widgets.search import ThreadlineWidget
+
+
+class SearchBuffer(Buffer):
+    """shows a result list of threads for a query"""
+
+    modename = 'search'
+    threads = []
+    _REVERSE = {'oldest_first': 'newest_first',
+                'newest_first': 'oldest_first'}
+
+    def __init__(self, ui, initialquery='', sort_order=None):
+        self.dbman = ui.dbman
+        self.ui = ui
+        self.querystring = initialquery
+        default_order = settings.get('search_threads_sort_order')
+        self.sort_order = sort_order or default_order
+        self.result_count = 0
+        self.isinitialized = False
+        self.proc = None  # process that fills our pipe
+        self.rebuild()
+        Buffer.__init__(self, ui, self.body)
+
+    def __str__(self):
+        formatstring = '[search] for "%s" (%d message%s)'
+        return formatstring % (self.querystring, self.result_count,
+                               's' if self.result_count > 1 else '')
+
+    def get_info(self):
+        info = {}
+        info['querystring'] = self.querystring
+        info['result_count'] = self.result_count
+        info['result_count_positive'] = 's' if self.result_count > 1 else ''
+        return info
+
+    def cleanup(self):
+        self.kill_filler_process()
+
+    def kill_filler_process(self):
+        """
+        terminates the process that fills this buffers
+        :class:`~alot.walker.PipeWalker`.
+        """
+        if self.proc:
+            if self.proc.is_alive():
+                self.proc.terminate()
+
+    def rebuild(self, reverse=False):
+        self.isinitialized = True
+        self.reversed = reverse
+        self.kill_filler_process()
+
+        if reverse:
+            order = self._REVERSE[self.sort_order]
+        else:
+            order = self.sort_order
+
+        exclude_tags = settings.get_notmuch_setting('search', 'exclude_tags')
+        if exclude_tags:
+            exclude_tags = [t for t in exclude_tags.split(';') if t]
+
+        try:
+            self.result_count = self.dbman.count_messages(self.querystring)
+            self.pipe, self.proc = self.dbman.get_threads(self.querystring,
+                                                          order,
+                                                          exclude_tags)
+        except NotmuchError:
+            self.ui.notify('malformed query string: %s' % self.querystring,
+                           'error')
+            self.listbox = urwid.ListBox([])
+            self.body = self.listbox
+            return
+
+        self.threadlist = PipeWalker(self.pipe, ThreadlineWidget,
+                                     dbman=self.dbman,
+                                     reverse=reverse)
+
+        self.listbox = urwid.ListBox(self.threadlist)
+        self.body = self.listbox
+
+    def get_selected_threadline(self):
+        """
+        returns curently focussed :class:`alot.widgets.ThreadlineWidget`
+        from the result list.
+        """
+        threadlinewidget, _ = self.threadlist.get_focus()
+        return threadlinewidget
+
+    def get_selected_thread(self):
+        """returns currently selected :class:`~alot.db.Thread`"""
+        threadlinewidget = self.get_selected_threadline()
+        thread = None
+        if threadlinewidget:
+            thread = threadlinewidget.get_thread()
+        return thread
+
+    def consume_pipe(self):
+        while not self.threadlist.empty:
+            self.threadlist._get_next_item()
+
+    def focus_first(self):
+        if not self.reversed:
+            self.body.set_focus(0)
+        else:
+            self.rebuild(reverse=False)
+
+    def focus_last(self):
+        if self.reversed:
+            self.body.set_focus(0)
+        elif self.result_count < 200 or self.sort_order not in self._REVERSE:
+            self.consume_pipe()
+            num_lines = len(self.threadlist.get_lines())
+            self.body.set_focus(num_lines - 1)
+        else:
+            self.rebuild(reverse=True)
+
diff --git a/alot/buffers/taglist.py b/alot/buffers/taglist.py
new file mode 100644
index 00000000..c0a652f7
--- /dev/null
+++ b/alot/buffers/taglist.py
@@ -0,0 +1,71 @@
+# Copyright (C) 2011-2018  Patrick Totzke <patricktotzke@gmail.com>
+# This file is released under the GNU GPL, version 3 or a later revision.
+# For further details see the COPYING file
+from __future__ import absolute_import
+import urwid
+
+from .buffer import Buffer
+from ..settings.const import settings
+from ..widgets.globals import TagWidget
+
+
+class TagListBuffer(Buffer):
+    """lists all tagstrings present in the notmuch database"""
+
+    modename = 'taglist'
+
+    def __init__(self, ui, alltags=None, filtfun=lambda x: x):
+        self.filtfun = filtfun
+        self.ui = ui
+        self.tags = alltags or []
+        self.isinitialized = False
+        self.rebuild()
+        Buffer.__init__(self, ui, self.body)
+
+    def rebuild(self):
+        if self.isinitialized:
+            focusposition = self.taglist.get_focus()[1]
+        else:
+            focusposition = 0
+            self.isinitialized = True
+
+        lines = list()
+        displayedtags = sorted((t for t in self.tags if self.filtfun(t)),
+                               key=str.lower)
+        for (num, b) in enumerate(displayedtags):
+            if (num % 2) == 0:
+                attr = settings.get_theming_attribute('taglist', 'line_even')
+            else:
+                attr = settings.get_theming_attribute('taglist', 'line_odd')
+            focus_att = settings.get_theming_attribute('taglist', 'line_focus')
+
+            tw = TagWidget(b, attr, focus_att)
+            rows = [('fixed', tw.width(), tw)]
+            if tw.hidden:
+                rows.append(urwid.Text(b + ' [hidden]'))
+            elif tw.translated is not b:
+                rows.append(urwid.Text('(%s)' % b))
+            line = urwid.Columns(rows, dividechars=1)
+            line = urwid.AttrMap(line, attr, focus_att)
+            lines.append(line)
+
+        self.taglist = urwid.ListBox(urwid.SimpleListWalker(lines))
+        self.body = self.taglist
+
+        self.taglist.set_focus(focusposition % len(displayedtags))
+
+    def focus_first(self):
+        """Focus the first line in the tag list."""
+        self.body.set_focus(0)
+
+    def focus_last(self):
+        allpos = self.taglist.body.positions(reverse=True)
+        if allpos:
+            lastpos = allpos[0]
+            self.body.set_focus(lastpos)
+
+    def get_selected_tag(self):
+        """returns selected tagstring"""
+        cols, _ = self.taglist.get_focus()
+        tagwidget = cols.original_widget.get_focus()
+        return tagwidget.tag
diff --git a/alot/buffers/thread.py b/alot/buffers/thread.py
new file mode 100644
index 00000000..1ad99c32
--- /dev/null
+++ b/alot/buffers/thread.py
@@ -0,0 +1,335 @@
+# Copyright (C) 2011-2018  Patrick Totzke <patricktotzke@gmail.com>
+# This file is released under the GNU GPL, version 3 or a later revision.
+# For further details see the COPYING file
+from __future__ import absolute_import
+import urwid
+import logging
+from urwidtrees import ArrowTree, TreeBox, NestedTree
+
+from .buffer import Buffer
+from ..settings.const import settings
+from ..widgets.thread import ThreadTree
+from .. import commands
+
+
+
+class ThreadBuffer(Buffer):
+    """displays a thread as a tree of messages"""
+
+    modename = 'thread'
+
+    def __init__(self, ui, thread):
+        """
+        :param ui: main UI
+        :type ui: :class:`~alot.ui.UI`
+        :param thread: thread to display
+        :type thread: :class:`~alot.db.Thread`
+        """
+        self.thread = thread
+        self.message_count = thread.get_total_messages()
+
+        # two semaphores for auto-removal of unread tag
+        self._auto_unread_dont_touch_mids = set([])
+        self._auto_unread_writing = False
+
+        self._indent_width = settings.get('thread_indent_replies')
+        self.rebuild()
+        Buffer.__init__(self, ui, self.body)
+
+    def __str__(self):
+        return '[thread] %s (%d message%s)' % (self.thread.get_subject(),
+                                               self.message_count,
+                                               's' * (self.message_count > 1))
+
+    def get_info(self):
+        info = {}
+        info['subject'] = self.thread.get_subject()
+        info['authors'] = self.thread.get_authors_string()
+        info['tid'] = self.thread.get_thread_id()
+        info['message_count'] = self.message_count
+        return info
+
+    def get_selected_thread(self):
+        """returns the displayed :class:`~alot.db.Thread`"""
+        return self.thread
+
+    def rebuild(self):
+        try:
+            self.thread.refresh()
+        except NonexistantObjectError:
+            self.body = urwid.SolidFill()
+            self.message_count = 0
+            return
+
+        self._tree = ThreadTree(self.thread)
+
+        # define A to be the tree to be wrapped by a NestedTree and displayed.
+        # We wrap the thread tree into an ArrowTree for decoration if
+        # indentation was requested and otherwise use it as is.
+        if self._indent_width == 0:
+            A = self._tree
+        else:
+            # we want decoration.
+            bars_att = settings.get_theming_attribute('thread', 'arrow_bars')
+            # only add arrow heads if there is space (indent > 1).
+            heads_char = None
+            heads_att = None
+            if self._indent_width > 1:
+                heads_char = u'\u27a4'
+                heads_att = settings.get_theming_attribute('thread',
+                                                           'arrow_heads')
+            A = ArrowTree(
+                self._tree,
+                indent=self._indent_width,
+                childbar_offset=0,
+                arrow_tip_att=heads_att,
+                arrow_tip_char=heads_char,
+                arrow_att=bars_att)
+
+        self._nested_tree = NestedTree(A, interpret_covered=True)
+        self.body = TreeBox(self._nested_tree)
+        self.message_count = self.thread.get_total_messages()
+
+    def render(self, size, focus=False):
+        if self.message_count == 0:
+            return self.body.render(size, focus)
+
+        if settings.get('auto_remove_unread'):
+            logging.debug('Tbuffer: auto remove unread tag from msg?')
+            msg = self.get_selected_message()
+            mid = msg.get_message_id()
+            focus_pos = self.body.get_focus()[1]
+            summary_pos = (self.body.get_focus()[1][0], (0,))
+            cursor_on_non_summary = (focus_pos != summary_pos)
+            if cursor_on_non_summary:
+                if mid not in self._auto_unread_dont_touch_mids:
+                    if 'unread' in msg.get_tags():
+                        logging.debug('Tbuffer: removing unread')
+
+                        def clear():
+                            self._auto_unread_writing = False
+
+                        self._auto_unread_dont_touch_mids.add(mid)
+                        self._auto_unread_writing = True
+                        msg.remove_tags(['unread'], afterwards=clear)
+                        fcmd = commands.globals.FlushCommand(silent=True)
+                        self.ui.apply_command(fcmd)
+                    else:
+                        logging.debug('Tbuffer: No, msg not unread')
+                else:
+                    logging.debug('Tbuffer: No, mid locked for autorm-unread')
+            else:
+                if not self._auto_unread_writing and \
+                   mid in self._auto_unread_dont_touch_mids:
+                    self._auto_unread_dont_touch_mids.remove(mid)
+                logging.debug('Tbuffer: No, cursor on summary')
+        return self.body.render(size, focus)
+
+    def get_selected_mid(self):
+        """returns Message ID of focussed message"""
+        return self.body.get_focus()[1][0]
+
+    def get_selected_message_position(self):
+        """returns position of focussed message in the thread tree"""
+        return self._sanitize_position((self.get_selected_mid(),))
+
+    def get_selected_messagetree(self):
+        """returns currently focussed :class:`MessageTree`"""
+        return self._nested_tree[self.body.get_focus()[1][:1]]
+
+    def get_selected_message(self):
+        """returns focussed :class:`~alot.db.message.Message`"""
+        return self.get_selected_messagetree()._message
+
+    def get_messagetree_positions(self):
+        """
+        returns a Generator to walk through all positions of
+        :class:`MessageTree` in the :class:`ThreadTree` of this buffer.
+        """
+        return [(pos,) for pos in self._tree.positions()]
+
+    def messagetrees(self):
+        """
+        returns a Generator of all :class:`MessageTree` in the
+        :class:`ThreadTree` of this buffer.
+        """
+        for pos in self._tree.positions():
+            yield self._tree[pos]
+
+    def refresh(self):
+        """refresh and flushe caches of Thread tree"""
+        self.body.refresh()
+
+    # needed for ui.get_deep_focus..
+    def get_focus(self):
+        "Get the focus from the underlying body widget."
+        return self.body.get_focus()
+
+    def set_focus(self, pos):
+        "Set the focus in the underlying body widget."
+        logging.debug('setting focus to %s ', pos)
+        self.body.set_focus(pos)
+
+    def focus_first(self):
+        """set focus to first message of thread"""
+        self.body.set_focus(self._nested_tree.root)
+
+    def focus_last(self):
+        self.body.set_focus(next(self._nested_tree.positions(reverse=True)))
+
+    def _sanitize_position(self, pos):
+        return self._nested_tree._sanitize_position(pos,
+                                                    self._nested_tree._tree)
+
+    def focus_selected_message(self):
+        """focus the summary line of currently focussed message"""
+        # move focus to summary (root of current MessageTree)
+        self.set_focus(self.get_selected_message_position())
+
+    def focus_parent(self):
+        """move focus to parent of currently focussed message"""
+        mid = self.get_selected_mid()
+        newpos = self._tree.parent_position(mid)
+        if newpos is not None:
+            newpos = self._sanitize_position((newpos,))
+            self.body.set_focus(newpos)
+
+    def focus_first_reply(self):
+        """move focus to first reply to currently focussed message"""
+        mid = self.get_selected_mid()
+        newpos = self._tree.first_child_position(mid)
+        if newpos is not None:
+            newpos = self._sanitize_position((newpos,))
+            self.body.set_focus(newpos)
+
+    def focus_last_reply(self):
+        """move focus to last reply to currently focussed message"""
+        mid = self.get_selected_mid()
+        newpos = self._tree.last_child_position(mid)
+        if newpos is not None:
+            newpos = self._sanitize_position((newpos,))
+            self.body.set_focus(newpos)
+
+    def focus_next_sibling(self):
+        """focus next sibling of currently focussed message in thread tree"""
+        mid = self.get_selected_mid()
+        newpos = self._tree.next_sibling_position(mid)
+        if newpos is not None:
+            newpos = self._sanitize_position((newpos,))
+            self.body.set_focus(newpos)
+
+    def focus_prev_sibling(self):
+        """
+        focus previous sibling of currently focussed message in thread tree
+        """
+        mid = self.get_selected_mid()
+        localroot = self._sanitize_position((mid,))
+        if localroot == self.get_focus()[1]:
+            newpos = self._tree.prev_sibling_position(mid)
+            if newpos is not None:
+                newpos = self._sanitize_position((newpos,))
+        else:
+            newpos = localroot
+        if newpos is not None:
+            self.body.set_focus(newpos)
+
+    def focus_next(self):
+        """focus next message in depth first order"""
+        mid = self.get_selected_mid()
+        newpos = self._tree.next_position(mid)
+        if newpos is not None:
+            newpos = self._sanitize_position((newpos,))
+            self.body.set_focus(newpos)
+
+    def focus_prev(self):
+        """focus previous message in depth first order"""
+        mid = self.get_selected_mid()
+        localroot = self._sanitize_position((mid,))
+        if localroot == self.get_focus()[1]:
+            newpos = self._tree.prev_position(mid)
+            if newpos is not None:
+                newpos = self._sanitize_position((newpos,))
+        else:
+            newpos = localroot
+        if newpos is not None:
+            self.body.set_focus(newpos)
+
+    def focus_property(self, prop, direction):
+        """does a walk in the given direction and focuses the
+        first message tree that matches the given property"""
+        newpos = self.get_selected_mid()
+        newpos = direction(newpos)
+        while newpos is not None:
+            MT = self._tree[newpos]
+            if prop(MT):
+                newpos = self._sanitize_position((newpos,))
+                self.body.set_focus(newpos)
+                break
+            newpos = direction(newpos)
+
+    def focus_next_matching(self, querystring):
+        """focus next matching message in depth first order"""
+        self.focus_property(lambda x: x._message.matches(querystring),
+                            self._tree.next_position)
+
+    def focus_prev_matching(self, querystring):
+        """focus previous matching message in depth first order"""
+        self.focus_property(lambda x: x._message.matches(querystring),
+                            self._tree.prev_position)
+
+    def focus_next_unfolded(self):
+        """focus next unfolded message in depth first order"""
+        self.focus_property(lambda x: not x.is_collapsed(x.root),
+                            self._tree.next_position)
+
+    def focus_prev_unfolded(self):
+        """focus previous unfolded message in depth first order"""
+        self.focus_property(lambda x: not x.is_collapsed(x.root),
+                            self._tree.prev_position)
+
+    def expand(self, msgpos):
+        """expand message at given position"""
+        MT = self._tree[msgpos]
+        MT.expand(MT.root)
+
+    def messagetree_at_position(self, pos):
+        """get :class:`MessageTree` for given position"""
+        return self._tree[pos[0]]
+
+    def expand_all(self):
+        """expand all messages in thread"""
+        for MT in self.messagetrees():
+            MT.expand(MT.root)
+
+    def collapse(self, msgpos):
+        """collapse message at given position"""
+        MT = self._tree[msgpos]
+        MT.collapse(MT.root)
+        self.focus_selected_message()
+
+    def collapse_all(self):
+        """collapse all messages in thread"""
+        for MT in self.messagetrees():
+            MT.collapse(MT.root)
+        self.focus_selected_message()
+
+    def unfold_matching(self, querystring, focus_first=True):
+        """
+        expand all messages that match a given querystring.
+
+        :param querystring: query to match
+        :type querystring: str
+        :param focus_first: set the focus to the first matching message
+        :type focus_first: bool
+        """
+        first = None
+        for MT in self.messagetrees():
+            msg = MT._message
+            if msg.matches(querystring):
+                MT.expand(MT.root)
+                if first is None:
+                    first = (self._tree.position_of_messagetree(MT), MT.root)
+                    self.body.set_focus(first)
+            else:
+                MT.collapse(MT.root)
+        self.body.refresh()
diff --git a/alot/ui.py b/alot/ui.py
index 16a5297b..b7490d03 100644
--- a/alot/ui.py
+++ b/alot/ui.py
@@ -11,7 +11,8 @@ from twisted.internet import reactor, defer, task
 import urwid
 
 from .settings.const import settings
-from .buffers import BufferlistBuffer, SearchBuffer
+from .buffers import BufferlistBuffer
+from .buffers import SearchBuffer
 from .commands import globals
 from .commands import commandfactory
 from .commands import CommandCanceled