diff --git a/src/pyj/book_list/home.pyj b/src/pyj/book_list/home.pyj
new file mode 100644
index 0000000000..dd685534cd
--- /dev/null
+++ b/src/pyj/book_list/home.pyj
@@ -0,0 +1,11 @@
+# vim:fileencoding=utf-8
+# License: GPL v3 Copyright: 2017, Kovid Goyal <kovid at kovidgoyal.net>
+from __python__ import hash_literals, bound_methods
+
+from book_list.ui import set_default_panel_handler
+
+
+def init():
+    pass
+
+set_default_panel_handler(init)
diff --git a/src/pyj/book_list/main.pyj b/src/pyj/book_list/main.pyj
index 5548817585..6c5a276d94 100644
--- a/src/pyj/book_list/main.pyj
+++ b/src/pyj/book_list/main.pyj
@@ -9,6 +9,7 @@ from dom import set_css, get_widget_css
 from modals import create_modal_container, error_dialog
 from session import get_interface_data, UserSessionData, update_interface_data, get_translations
 from gettext import gettext as _, install
+from popups import install_event_filters
 from utils import parse_url_params
 
 from book_list.constants import book_list_container_id, read_book_container_id
@@ -36,6 +37,7 @@ def onerror(msg, script_url, line_number, column_number, error_object):
         console.log('There was an error in the unhandled exception handler')
 
 def init_ui():
+    install_event_filters()
     set_default_mode_handler(book_list_mode_handler)
     window.onerror = onerror
     translations = get_translations()
diff --git a/src/pyj/book_list/top_bar.pyj b/src/pyj/book_list/top_bar.pyj
index 418582766d..695a38370e 100644
--- a/src/pyj/book_list/top_bar.pyj
+++ b/src/pyj/book_list/top_bar.pyj
@@ -26,104 +26,83 @@ add_extra_css(def():
     return style
 )
 
-class TopBar:
+def create_markup(container_id):
+    container = document.getElementById(container_id)
+    for i in range(2):
+        bar = E.div(
+            class_=CLASS_NAME,
+            E.div(style="white-space:nowrap; overflow:hidden; text-overflow: ellipsis; padding-left: 0.5em;"),
+            E.div(style="white-space:nowrap; text-align:right; padding-right: 0.5em;")
+        )
+        if i is 0:
+            set_css(bar, position='fixed', left='0', top='0', z_index='1')
+        set_css(bar,
+            width='100%', display='flex', flex_direction='row', flex_wrap='wrap', justify_content='space-between',
+            font_size=get_font_size('title'), user_select='none',
+            color=get_color('bar-foreground'), background_color=get_color('bar-background')
+        )
+        container.appendChild(bar)
 
-    def __init__(self, book_list_container):
-        nonlocal bar_counter
-        bar_counter += 1
-        self.current_left_data = {}
-        self.bar_id, self.dummy_bar_id = 'top-bar-' + bar_counter, 'dummy-top-bar-' + bar_counter
-        for bid in self.dummy_bar_id, self.bar_id:
-            bar = E.div(
-                id=bid, class_=CLASS_NAME,
-                E.div(style="white-space:nowrap; overflow:hidden; text-overflow: ellipsis; padding-left: 0.5em;"),
-                E.div(style="white-space:nowrap; text-align:right; padding-right: 0.5em;")
-            )
-            if bid is self.bar_id:
-                set_css(bar, position='fixed', left='0', top='0', z_index='1')
-            set_css(bar,
-                width='100%', display='flex', flex_direction='row', flex_wrap='wrap', justify_content='space-between',
-                font_size=get_font_size('title'), user_select='none',
-                color=get_color('bar-foreground'), background_color=get_color('bar-background')
-            )
-            book_list_container.appendChild(bar)
+def get_bars(container_id):
+    container = document.getElementById(container_id)
+    return container.getElementsByClassName(CLASS_NAME)
 
-    @property
-    def bar(self):
-        return document.getElementById(self.bar_id)
+def set_left_data(container_id, title='calibre', icon_name='heart', action=None, tooltip='', run_animation=False, title_action=None, title_tooltip=None):
+    bars = get_bars(container_id)
+    if icon_name is 'heart':
+        if not tooltip:
+            tooltip = _('Donate to support calibre development')
 
-    @property
-    def dummy_bar(self):
-        return document.getElementById(self.dummy_bar_id)
+    for i, bar in enumerate(bars):
+        left = bar.firstChild
+        clear(left)
+        title_elem = 'a' if callable(title_action) else 'span'
+        left.appendChild(E.a(title=tooltip, svgicon(icon_name)))
+        left.appendChild(E(title_elem, title, title=title_tooltip, class_='top-bar-title',
+            style='margin-left: {0}; font-weight: bold; padding-top: {1}; padding-bottom: {1}; vertical-align: middle'.format(SPACING, VSPACING)))
+        if i is 0:
+            a = left.firstChild
+            if icon_name is 'heart':
+                set_css(a,
+                    animation_name=THROBBER_NAME, animation_duration='1s', animation_timing_function='ease-in-out',
+                    animation_iteration_count='5', animation_play_state='running' if run_animation else 'paused'
+                )
+                set_css(a.firstChild, color=get_color('heart'))
+                a.setAttribute('href', 'http://calibre-ebook.com/donate')
+                a.setAttribute('target', 'donate-to-calibre')
+            if action is not None:
+                a.addEventListener('click', def(event): event.preventDefault(), action();)
 
-    def set_left(self, title='calibre', icon_name='heart', action=None, tooltip='', run_animation=False):
-        self.current_left_data = {'title':title, 'icon_name':icon_name, 'action':action, 'tooltip':tooltip}
-        if icon_name is 'heart':
-            if not tooltip:
-                tooltip = _('Donate to support calibre development')
+            if callable(title_action):
+                a = a.nextSibling
+                a.addEventListener('click', def(event): event.preventDefault(), title_action();)
 
-        title_action = title_tooltip = None
-        if callable(title):
-            data = title()
-            title, title_action, title_tooltip = data.title, data.title_action, data.title_tooltip
+def set_title(container_id, text):
+    bars = get_bars(container_id)
+    for bar in bars:
+        bar.firstChild.firstChild.nextSibling.textContent = text
 
-        for bar in self.bar, self.dummy_bar:
-            left = bar.firstChild
-            clear(left)
-            title_elem = 'a' if callable(title_action) else 'span'
-            left.appendChild(E.a(title=tooltip, svgicon(icon_name)))
-            left.appendChild(E(title_elem, title, title=title_tooltip, class_='top-bar-title',
-                style='margin-left: {0}; font-weight: bold; padding-top: {1}; padding-bottom: {1}; vertical-align: middle'.format(SPACING, VSPACING)))
-            if bar is self.bar:
-                a = left.firstChild
-                if icon_name is 'heart':
-                    set_css(a,
-                        animation_name=THROBBER_NAME, animation_duration='1s', animation_timing_function='ease-in-out',
-                        animation_iteration_count='5', animation_play_state='running' if run_animation else 'paused'
-                    )
-                    set_css(a.firstChild, color=get_color('heart'))
-                    a.setAttribute('href', 'http://calibre-ebook.com/donate')
-                    a.setAttribute('target', 'donate-to-calibre')
-                if action is not None:
-                    a.addEventListener('click', def(event): event.preventDefault(), action();)
+def create_top_bar(container_id):
+    create_markup(container_id)
 
-                if callable(title_action):
-                    a = a.nextSibling
-                    a.addEventListener('click', def(event): event.preventDefault(), title_action();)
+def add_button(container_id, icon_name=None, action=None, tooltip=''):
+    if not icon_name:
+        return
+    bars = get_bars(container_id)
+    for bar in bars:
+        right = bar.firstChild.nextSibling
+        right.appendChild(E.a(
+            style="margin-left: " + SPACING,
+            title=tooltip, svgicon(icon_name),
+        ))
+        right.lastChild.setAttribute('id', ('top' if bar is self.bar else 'dummy') + '-bar-icon-' + icon_name)
+        if bar is self.bar:
+            if action is not None:
+                right.lastChild.addEventListener('click', def(event): event.preventDefault(), action();)
 
-    def refresh_left(self):
-        kw = self.current_left_data
-        self.set_left(**kw)
-
-    def add_button(self, icon_name=None, action=None, tooltip=''):
-        if not icon_name:
-            return
-        for bar in self.bar, self.dummy_bar:
-            right = bar.firstChild.nextSibling
-            right.appendChild(E.a(
-                style="margin-left: " + SPACING,
-                title=tooltip, svgicon(icon_name),
-            ))
-            right.lastChild.setAttribute('id', ('top' if bar is self.bar else 'dummy') + '-bar-icon-' + icon_name)
-            if bar is self.bar:
-                if action is not None:
-                    right.lastChild.addEventListener('click', def(event): event.preventDefault(), action();)
-
-    def set_button_visibility(self, icon_name, visible):
-        for bar in self.bar, self.dummy_bar:
-            right = bar.firstChild.nextSibling
-            elem = right.querySelector('#{}-bar-icon-{}'.format(('top' if bar is self.bar else 'dummy'), icon_name))
-            if elem:
-                elem.style.display = 'inline-block' if visible else 'none'
-
-    def apply_state(self, left, buttons):
-        self.set_left(**left)
-        for bar in self.bar, self.dummy_bar:
-            right = bar.firstChild.nextSibling
-            clear(right)
-        for button in buttons:
-            self.add_button(**button)
-
-    def set_title(self, text):
-        for bar in self.bar, self.dummy_bar:
-            bar.firstChild.firstChild.nextSibling.textContent = text
+def set_button_visibility(container_id, icon_name, visible):
+    for bar in get_bars(container_id):
+        right = bar.firstChild.nextSibling
+        elem = right.querySelector('#{}-bar-icon-{}'.format(('top' if bar is self.bar else 'dummy'), icon_name))
+        if elem:
+            elem.style.display = 'inline-block' if visible else 'none'
diff --git a/src/pyj/book_list/ui.pyj b/src/pyj/book_list/ui.pyj
index 70e2de6d84..9a633e839e 100644
--- a/src/pyj/book_list/ui.pyj
+++ b/src/pyj/book_list/ui.pyj
@@ -1,251 +1,13 @@
 # vim:fileencoding=utf-8
 # License: GPL v3 Copyright: 2015, Kovid Goyal <kovid at kovidgoyal.net>
-from __python__ import hash_literals
+from __python__ import hash_literals, bound_methods
 
-import traceback
 from dom import ensure_id, clear
 from elementmaker import E
-from gettext import gettext as _
-from modals import error_dialog, ajax_progress_dialog
-from popups import install_event_filters
 
 from book_list.constants import book_list_container_id
-from book_list.globals import get_boss, get_session_data, get_current_query
-from book_list.search import SearchPanel
-from book_list.top_bar import TopBar
-from book_list.views import BooksView
-from book_list.item_list import ItemsView, create_item
-from book_list.prefs import PrefsPanel
-from book_list.book_details import BookDetailsPanel
+from book_list.globals import get_current_query
 
-class BarState:
-
-    def __init__(self, **kw):
-        self.left_state = kw
-        self.buttons = v'[]'
-
-    def add_button(self, **kw):
-        self.buttons.push(kw)
-
-class ClosePanelBar(BarState):
-
-    def __init__(self, title, tooltip='', close_callback=None):
-        tooltip = tooltip or _('Close this panel')
-        def action():
-            close_panel()
-            if close_callback is not None:
-                close_callback()
-        BarState.__init__(self, title=title, tooltip=tooltip, action=action, icon_name='close')
-
-class UIState:
-
-    def __init__(self, top_bar_state=None, main_panel=None, panel_data=None):
-        self.top_bar_state = top_bar_state
-        self.main_panel = main_panel
-        self.panel_data = panel_data
-
-    def add_button(self, **kw):
-        self.top_bar_state.add_button(**kw)
-
-def close_panel():
-    get_boss().ui.close_panel()
-
-def replace_panel_action(replacement):
-    return def():
-        get_boss().ui.replace_panel(replacement)
-
-def show_panel_action(key):
-    return def():
-        get_boss().ui.show_panel(key)
-
-
-def create_book_view_top_bar_state(books_view):
-    ibs = BarState(run_animation=True, title=def():
-        q = books_view.interface_data['search_result']['query']
-        if q:
-            return {'title': _('Books matching') + '::  ' + q, 'title_tooltip':_('Click to clear this search'),
-                    'title_action':def():
-                books_view.change_search('')
-            }
-        return {'title': 'calibre'}
-    )
-    ibs.add_button(icon_name='sort-amount-desc', tooltip=_('Sort books'), action=show_panel_action('booklist-sort-menu'))
-    ibs.add_button(icon_name='search', tooltip=_('Search for books'), action=show_panel_action('booklist-search'))
-    ibs.add_button(icon_name='ellipsis-v', tooltip=_('More actions'), action=show_panel_action('more-actions-menu'))
-    return ibs
-
-def random_book():
-    get_boss().ui.replace_panel('book-details', extra_query_data={'book-id':'0'})
-
-def change_library_actions():
-    boss = get_boss()
-    interface_data = boss.interface_data
-    ans = []
-    ans.subtitle = _('Currently showing the library: ') + interface_data.library_map[interface_data.library_id]
-    for lid in sorted(interface_data.library_map):
-        if lid is not interface_data.library_id:
-            library_name = interface_data.library_map[lid]
-            ans.append({'title':library_name, 'action':boss.ui.change_library.bind(boss.ui, lid)})
-    return ans
-
-class DevelopPanel:
-
-    # To use, go to URL:
-    # http://localhost:8080/?panel=develop-widgets&widget_module=<module name>
-    # Implement the develop(container) method in that module.
-
-    def __init__(self, interface_data, book_list_container):
-        c = E.div()
-        book_list_container.appendChild(c)
-        self.container_id = ensure_id(c)
-
-    @property
-    def container(self):
-        return document.getElementById(self.container_id)
-
-    @property
-    def is_visible(self):
-        self.container.style.display is 'block'
-
-    @is_visible.setter
-    def is_visible(self, val):
-        self.container.style.display = 'block' if val else 'none'
-
-    def init(self):
-        q = get_current_query()
-        m = q.widget_module
-        if m:
-            m = get_module(m)
-            if m?.develop:
-                m.develop(self.container)
-            else:
-                self.container.textContent = 'The module {} either does not exist or has no develop method.'.format(q.widget_module)
-
-
-class UI:
-
-    ROOT_PANEL = 'books'
-
-    def __init__(self, interface_data, book_list_container):
-        install_event_filters()
-        self.top_bar = TopBar(book_list_container)
-        self.books_view = BooksView(interface_data, book_list_container)
-        self.items_view = ItemsView(interface_data, book_list_container)
-        self.prefs_panel = PrefsPanel(interface_data, book_list_container)
-        self.search_panel = SearchPanel(interface_data, book_list_container)
-        self.book_details_panel = BookDetailsPanel(interface_data, book_list_container)
-        self.develop_panel = DevelopPanel(interface_data, book_list_container)
-        self.panels = [self.books_view, self.items_view, self.search_panel, self.prefs_panel, self.book_details_panel]
-        self.panel_map = {self.ROOT_PANEL: UIState(create_book_view_top_bar_state(self.books_view), main_panel=self.books_view)}
-        self.current_panel = self.ROOT_PANEL
-
-        num_of_libraries = len(interface_data.library_map)
-        actions = [
-            create_item(_('Book List Mode'), replace_panel_action('booklist-mode-menu'), _('Change how the list of books is displayed')),
-            create_item(_('A Random Book'), random_book, _('Choose a random book from your library')),
-        ]
-        if num_of_libraries > 1:
-            actions.push(
-                create_item(_('Change Library'), replace_panel_action('booklist-change-library'), _('Choose a different library to display'))
-            )
-            self.panel_map['booklist-change-library'] = UIState(ClosePanelBar(_('Change Library')), panel_data=change_library_actions)
-
-        self.panel_map['more-actions-menu'] = UIState(ClosePanelBar(_('More actions')), panel_data=actions)
-
-        self.panel_map['booklist-mode-menu'] = UIState(ClosePanelBar(_('Book List Mode')), panel_data=[])
-
-        self.panel_map['booklist-sort-menu'] = UIState(ClosePanelBar(_('Sort books')), panel_data=def():
-            return self.books_view.sort_panel_data(create_item)
-        )
-        self.panel_map['booklist-config-tb'] = self.create_prefences_panel(
-            _('Configure Tag Browser'), close_callback=self.search_panel.apply_prefs.bind(self.search_panel),
-            panel_data=self.search_panel.get_prefs.bind(self.search_panel))
-        self.panel_map['develop-widgets'] = UIState(ClosePanelBar('Develop widgets'), main_panel=self.develop_panel)
-
-        bss = ClosePanelBar(_('Search for books'))
-        bss.add_button(icon_name='cogs', tooltip=_('Configure Tag Browser'), action=show_panel_action('booklist-config-tb'))
-        self.panel_map['booklist-search'] = UIState(bss, main_panel=self.search_panel)
-
-        self.panel_map['book-details'] = bd = UIState(ClosePanelBar(_('Book Details')), main_panel=self.book_details_panel)
-        bd.add_button(icon_name='random', tooltip=_('Pick another random book'), action=self.book_details_panel.show_random.bind(self.book_details_panel))
-        # bd.add_button(icon_name='book', tooltip=_('Read this book'), action=self.book_details_panel.read_book.bind(self.book_details_panel))
-        # bd.add_button(icon_name='cloud-download', tooltip=_('Download this book'), action=self.book_details_panel.download_book.bind(self.book_details_panel))
-
-    def create_prefences_panel(self, title, close_callback=None, panel_data=None):
-        ans = UIState(ClosePanelBar(title), close_callback=close_callback, main_panel=self.prefs_panel, panel_data=panel_data)
-        ans.add_button(icon_name='refresh', tooltip=_('Restore default settings'), action=self.prefs_panel.reset_to_defaults.bind(self.prefs_panel))
-        return ans
-
-    def set_title(self, text):
-        self.top_bar.set_title(text)
-
-    def set_button_visibility(self, icon_name, visible):
-        self.top_bar.set_button_visibility(icon_name, visible)
-
-    def on_resize(self):
-        pass
-
-    def apply_state(self):
-        window.scrollTo(0, 0)
-        state = self.panel_map[self.current_panel]
-        self.top_bar.apply_state(state.top_bar_state.left_state, state.top_bar_state.buttons)
-        main_panel = state.main_panel or self.items_view
-        for panel in self.panels:
-            panel.is_visible = panel is main_panel
-        if callable(main_panel.init):
-            panel_data = state.panel_data() if callable(state.panel_data) else state.panel_data
-            main_panel.init(panel_data)
-        if self.current_panel is self.ROOT_PANEL:
-            # only run the beating heart animation once
-            window.setTimeout(def(): state.top_bar_state.left_state.run_animation = False;, 10)
-
-    def close_panel(self):
-        if get_boss().has_history:
-            window.history.back()
-        else:
-            self.show_panel(self.ROOT_PANEL)
-
-    def replace_panel(self, panel_name, force=False, extra_query_data=None):
-        action_needed = force or panel_name is not self.current_panel
-        if action_needed:
-            self.current_panel = panel_name or self.ROOT_PANEL
-        get_boss().push_state(replace=True, extra_query_data=extra_query_data)
-        if action_needed:
-            self.apply_state()
-
-    def show_panel(self, panel_name, push_state=True, force=False, extra_query_data=None):
-        action_needed = force or panel_name is not self.current_panel
-        if action_needed:
-            self.current_panel = panel_name or self.ROOT_PANEL
-        if push_state:
-            get_boss().push_state(extra_query_data=extra_query_data)
-        if action_needed:
-            self.apply_state()
-
-    def refresh_books_view(self):
-        self.books_view.refresh()
-        if self.current_panel is self.ROOT_PANEL:
-            self.top_bar.refresh_left()
-
-    def change_library(self, library_id):
-        data = {'search':'', 'sort':get_session_data().get_library_option(library_id, 'sort'), 'library_id':library_id}
-        ajax_progress_dialog('interface-data/get-books', self.library_changed.bind(self), _(
-            'Fetching data from server, please wait') + '…', query=data, extra_data_for_callback={'library_id':library_id})
-
-    def library_changed(self, end_type, xhr, ev):
-        if end_type is 'load':
-            boss = get_boss()
-            boss.interface_data.library_id = xhr.extra_data_for_callback.library_id
-            try:
-                data = JSON.parse(xhr.responseText)
-                boss.change_books(data)
-            except Exception as err:
-                return error_dialog(_('Could not change library'), err + '', details=traceback.format_exc())
-            self.show_panel(self.ROOT_PANEL)
-            window.scrollTo(0, 0)
-        elif end_type is not 'abort':
-            msg = xhr.error_html
-            error_dialog(_('Could not change library'), msg)
 
 panel_handlers = {}
 default_panel_handler = None
@@ -260,6 +22,21 @@ def set_default_panel_handler(handler):
     default_panel_handler = handler
 
 
+def develop_panel(container):
+    # To use, go to URL:
+    # http://localhost:8080/?panel=develop-widgets&widget_module=<module name>
+    # Implement the develop(container) method in that module.
+    q = get_current_query()
+    m = q.widget_module
+    if m:
+        m = get_module(m)
+        if m?.develop:
+            m.develop(container)
+        else:
+            container.textContent = 'The module {} either does not exist or has no develop method.'.format(q.widget_module)
+
+set_panel_handler('develop-widgets', develop_panel)
+
 
 def apply_url_state(state):
     panel = state.panel or 'home'
@@ -269,3 +46,5 @@ def apply_url_state(state):
     clear(c)
     c.appendChild(E.div()), c.appendChild(E.div(style='display:none'))
     c.dataset.panel = panel
+    handler = panel_handlers[panel] or default_panel_handler
+    handler(ensure_id(c.firstChild, 'panel'))