Rework Gajim Theming

- Save all Theme settings to .css instead of the config file
- Add a gajim-dark.css
- Refactor the ThemesWindow

gajim/application.py

@@ -160,9 +160,7 @@ class GajimApplication(Gtk.Application):
             self.interface.roster.window.present()
             return
         from gajim.gui_interface import Interface
-        from gajim import gtkgui_helpers
         self.interface = Interface()
-        gtkgui_helpers.load_css()
         self.interface.run(self)
         self.add_actions()
         from gajim import gui_menu_builder

gajim/chat_control.py

@@ -674,7 +674,6 @@ class ChatControl(ChatControlBase):
             status_reduced = ''
         status_escaped = GLib.markup_escape_text(status_reduced)
 
-        font_attrs, font_attrs_small = self.get_font_attrs()
         st = app.config.get('displayed_chat_state_notifications')
         cs = contact.chatstate
         if cs and st in ('composing_only', 'all'):
@@ -685,22 +684,21 @@ class ChatControl(ChatControlBase):
             else:
                 chatstate = ''
 
-            label_text = '<span %s>%s</span><span %s>%s %s</span>' \
-                % (font_attrs,  name, font_attrs_small, acct_info, chatstate)
+            label_text = '<span>%s</span><span size="x-small" weight="light">%s %s</span>' \
+                % (name, acct_info, chatstate)
             if acct_info:
                 acct_info = i18n.direction_mark + ' ' + acct_info
             label_tooltip = '%s%s %s' % (name, acct_info, chatstate)
         else:
-            # weight="heavy" size="x-large"
-            label_text = '<span %s>%s</span><span %s>%s</span>' % \
-                    (font_attrs, name, font_attrs_small, acct_info)
+            label_text = '<span>%s</span><span size="x-small" weight="light">%s</span>' % \
+                    (name, acct_info)
             if acct_info:
                 acct_info = i18n.direction_mark + ' ' + acct_info
             label_tooltip = '%s%s' % (name, acct_info)
 
         if status_escaped:
             status_text = self.urlfinder.sub(self.make_href, status_escaped)
-            status_text = '<span %s>%s</span>' % (font_attrs_small, status_text)
+            status_text = '<span size="x-small" weight="light">%s</span>' % status_text
             self.banner_status_label.set_tooltip_text(status)
             self.banner_status_label.set_no_show_all(False)
             self.banner_status_label.show()
@@ -881,7 +879,7 @@ class ChatControl(ChatControlBase):
         if self.correcting:
             self.correcting = False
             gtkgui_helpers.remove_css_class(
-                self.msg_textview, 'msgcorrectingcolor')
+                self.msg_textview, 'gajim-msg-correcting')
 
         self.print_conversation(obj.message, self.contact.jid, tim=obj.timestamp,
             encrypted=obj.encrypted, xep0184_id=xep0184_id, xhtml=obj.xhtml,

gajim/chat_control_base.py

@@ -38,6 +38,7 @@ from gi.repository import Gio
 from gajim import gtkgui_helpers
 from gajim import message_control
 from gajim.gtk import NonModalConfirmationDialog
+from gajim.gtk.util import convert_rgb_to_hex
 from gajim import notify
 import re
 
@@ -52,6 +53,7 @@ from gajim.conversation_textview import ConversationTextview
 from gajim.message_textview import MessageTextView
 from gajim.common.contacts import GC_Contact
 from gajim.common.connection_handlers_events import MessageOutgoingEvent
+from gajim.common.const import StyleAttr
 
 from gajim.command_system.implementation.middleware import ChatCommandProcessor
 from gajim.command_system.implementation.middleware import CommandTools
@@ -87,40 +89,13 @@ class ChatControlBase(MessageControl, ChatCommandProcessor, CommandTools):
         keycode_ins = None
 
     def make_href(self, match):
-        url_color = app.config.get('urlmsgcolor')
+        url_color = app.css_config.get_value('.gajim-url', StyleAttr.COLOR)
+        color = convert_rgb_to_hex(url_color)
         url = match.group()
-        if not '://' in url:
+        if '://' not in url:
             url = 'http://' + url
-        return '<a href="%s"><span color="%s">%s</span></a>' % (url,
-                url_color, match.group())
-
-    def get_font_attrs(self):
-        """
-        Get pango font attributes for banner from theme settings
-        """
-        theme = app.config.get('roster_theme')
-        bannerfont = app.config.get_per('themes', theme, 'bannerfont')
-        bannerfontattrs = app.config.get_per('themes', theme, 'bannerfontattrs')
-
-        if bannerfont:
-            font = Pango.FontDescription(bannerfont)
-        else:
-            font = Pango.FontDescription('Normal')
-        if bannerfontattrs:
-            # B attribute is set by default
-            if 'B' in bannerfontattrs:
-                font.set_weight(Pango.Weight.HEAVY)
-            if 'I' in bannerfontattrs:
-                font.set_style(Pango.Style.ITALIC)
-
-        font_attrs = 'font_desc="%s"' % font.to_string()
-
-        # in case there is no font specified we use x-large font size
-        if font.get_size() == 0:
-            font_attrs = '%s size="x-large"' % font_attrs
-        font.set_weight(Pango.Weight.NORMAL)
-        font_attrs_small = 'font_desc="%s" size="small"' % font.to_string()
-        return (font_attrs, font_attrs_small)
+        return '<a href="%s"><span foreground="%s">%s</span></a>' % (
+            url, color, match.group())
 
     def get_nb_unread(self):
         jid = self.contact.jid
@@ -381,6 +356,8 @@ class ChatControlBase(MessageControl, ChatCommandProcessor, CommandTools):
             self._nec_ping)
         app.ged.register_event_handler('sec-label-received', ged.GUI1,
             self._sec_labels_received)
+        app.ged.register_event_handler('style-changed', ged.GUI1,
+            self._style_changed)
 
         # This is basically a very nasty hack to surpass the inability
         # to properly use the super, because of the old code.
@@ -557,6 +534,9 @@ class ChatControlBase(MessageControl, ChatCommandProcessor, CommandTools):
             self._nec_our_status)
         app.ged.remove_event_handler('sec-label-received', ged.GUI1,
             self._sec_labels_received)
+        app.ged.remove_event_handler('style-changed', ged.GUI1,
+            self._style_changed)
+
 
     def on_msg_textview_populate_popup(self, textview, menu):
         """
@@ -1099,6 +1079,9 @@ class ChatControlBase(MessageControl, ChatCommandProcessor, CommandTools):
     def on_clear_formatting_menuitem_activate(self, widget):
         self.msg_textview.clear_tags()
 
+    def _style_changed(self, *args):
+        self.update_tags()
+
     def update_tags(self):
         self.conv_textview.update_tags()
 
@@ -1365,14 +1348,14 @@ class ChatControlBase(MessageControl, ChatCommandProcessor, CommandTools):
         history[pos - 1].startswith('/') or history[pos - 1].startswith('/me')):
             self.correcting = True
             gtkgui_helpers.add_css_class(
-                self.msg_textview, 'msgcorrectingcolor')
+                self.msg_textview, 'gajim-msg-correcting')
             message = history[pos - 1]
             msg_buf.set_text(message)
             return
         if self.correcting:
             # We were previously correcting
             gtkgui_helpers.remove_css_class(
-                self.msg_textview, 'msgcorrectingcolor')
+                self.msg_textview, 'gajim-msg-correcting')
         self.correcting = False
         pos += -1 if direction == 'up' else +1
         if pos == -1:

gajim/common/app.py

@@ -43,6 +43,7 @@ from gajim.common import configpaths
 from gajim.common import ged as ged_module
 from gajim.common.contacts import LegacyContactsAPI
 from gajim.common.events import Events
+from gajim.common.css_config import CSSConfig
 
 interface = None # The actual interface (the gtk one for the moment)
 thread_interface = lambda *args: None # Interface to run a thread and then a callback
@@ -66,6 +67,8 @@ gajimpaths = configpaths.gajimpaths
 
 RecentGroupchat = namedtuple('RecentGroupchat', ['room', 'server', 'nickname'])
 
+css_config = None
+
 os_info = None # used to cache os information
 
 transport_type = {} # list the type of transport
@@ -625,3 +628,7 @@ def get_app_window(cls, account=None):
                     continue
             return win
     return None
+
+def load_css_config():
+    global css_config
+    css_config = CSSConfig()

gajim/common/config.py

@@ -92,13 +92,6 @@ class Config:
             'mood_iconset': [ opt_str, DEFAULT_MOOD_ICONSET, '', True ],
             'activity_iconset': [ opt_str, DEFAULT_ACTIVITY_ICONSET, '', True ],
             'use_transports_iconsets': [ opt_bool, True, '', True ],
-            'inmsgcolor': [ opt_color, '#a40000', _('Incoming nickname color.'), True ],
-            'outmsgcolor': [ opt_color, '#3465a4', _('Outgoing nickname color.'), True ],
-            'inmsgtxtcolor': [ opt_color, '', _('Incoming text color.'), True ],
-            'outmsgtxtcolor': [ opt_color, '#555753', _('Outgoing text color.'), True ],
-            'statusmsgcolor': [ opt_color, '#4e9a06', _('Status message text color.'), True ],
-            'markedmsgcolor': [ opt_color, '#ff8080', '', True ],
-            'urlmsgcolor': [ opt_color, '#204a87', '', True ],
             'notif_signin_color': [ opt_color, '#32CD32', _('Contact signed in notification color.') ], # limegreen
             'notif_signout_color': [ opt_color, '#FF0000', _('Contact signout notification color') ], # red
             'notif_message_color': [ opt_color, '#1E90FF', _('New message notification color.') ], # dodgerblue
@@ -108,11 +101,6 @@ class Config:
             'notif_invite_color': [ opt_color, '#D2B48C', _('Groupchat invitation notification color') ], # tan1
             'notif_status_color': [ opt_color, '#D8BFD8', _('Background color of status changed notification') ], # thistle2
             'notif_other_color': [ opt_color, '#FFFFFF', _('Other dialogs color.') ], # white
-            'inmsgfont': [ opt_str, '', _('Incoming nickname font.'), True ],
-            'outmsgfont': [ opt_str, '', _('Outgoing nickname font.'), True ],
-            'inmsgtxtfont': [ opt_str, '', _('Incoming text font.'), True ],
-            'outmsgtxtfont': [ opt_str, '', _('Outgoing text font.'), True ],
-            'statusmsgfont': [ opt_str, '', _('Status message text font.'), True ],
             'collapsed_rows': [ opt_str, '', _('List (space separated) of rows (accounts and groups) that are collapsed.'), True ],
             'roster_theme': [ opt_str, _('default'), '', True ],
             'mergeaccounts': [ opt_bool, False, '', True ],
@@ -205,7 +193,6 @@ class Config:
             'notify_on_file_complete': [opt_bool, True],
             'file_transfers_port': [opt_int, 28011],
             'ft_add_hosts_to_send': [opt_str, '', _('Comma separated list of sent hosts, in addition of local interfaces, for File Transfer in case of address translation/port forwarding.')],
-            'conversation_font': [opt_str, ''],
             'use_kib_mib': [opt_bool, False, _('IEC standard says KiB = 1024 bytes, KB = 1000 bytes.')],
             'notify_on_all_muc_messages': [opt_bool, False],
             'trayicon_notification_on_events': [opt_bool, True, _('Notify of events in the notification area.')],
@@ -249,9 +236,6 @@ class Config:
             'print_status_in_muc': [opt_str, 'none', _('Can be "none", "all" or "in_and_out". If "none", Gajim will no longer print status line in groupchats when a member changes their status and/or their status message. If "all" Gajim will print all status messages. If "in_and_out", Gajim will only print FOO enters/leaves group chat.')],
             'log_contact_status_changes': [opt_bool, False],
             'log_xhtml_messages': [opt_bool, False, _('Log XHTML messages instead of plain text messages.')],
-            'just_connected_bg_color': [opt_str, '#adc3c6', _('Background color of contacts when they just signed in.')],
-            'just_disconnected_bg_color': [opt_str, '#ab6161', _('Background color of contacts when they just signed out.')],
-            'restored_messages_color': [opt_color, '#555753'],
             'restored_messages_small': [opt_bool, True, _('If true, restored messages will use a smaller font than the default one.')],
             'hide_avatar_of_transport': [opt_bool, False, _('Don\'t show avatar for the transport itself.')],
             'roster_window_skip_taskbar': [opt_bool, False, _('Don\'t show roster in the system taskbar.')],
@@ -438,35 +422,7 @@ class Config:
                     'bosh_http_pipelining': [ opt_bool, False ],
                     'bosh_wait_for_restart_response': [ opt_bool, False ],
             }, {}),
-            'themes': ({
-                    'accounttextcolor': [ opt_color, 'black', '', True ],
-                    'accountbgcolor': [ opt_color, 'white', '', True ],
-                    'accountfont': [ opt_str, '', '', True ],
-                    'accountfontattrs': [ opt_str, 'B', '', True ],
-                    'grouptextcolor': [ opt_color, 'black', '', True ],
-                    'groupbgcolor': [ opt_color, 'white', '', True ],
-                    'groupfont': [ opt_str, '', '', True ],
-                    'groupfontattrs': [ opt_str, 'I', '', True ],
-                    'contacttextcolor': [ opt_color, 'black', '', True ],
-                    'contactbgcolor': [ opt_color, 'white', '', True ],
-                    'contactfont': [ opt_str, '', '', True ],
-                    'contactfontattrs': [ opt_str, '', '', True ],
-                    'bannertextcolor': [ opt_color, 'black', '', True ],
-                    'bannerbgcolor': [ opt_color, '', '', True ],
-                    'bannerfont': [ opt_str, '', '', True ],
-                    'bannerfontattrs': [ opt_str, 'B', '', True ],
-                    'msgcorrectingcolor': [opt_color, '#eee8aa'],
-
-                    # http://www.pitt.edu/~nisg/cis/web/cgi/rgb.html
-                    'state_inactive_color': [ opt_color, 'grey62' ],
-                    'state_composing_color': [ opt_color, 'green4' ],
-                    'state_paused_color': [ opt_color, 'mediumblue' ],
-                    'state_gone_color': [ opt_color, 'grey' ],
-
-                    # MUC chat states
-                    'state_muc_msg_color': [ opt_color, 'mediumblue' ],
-                    'state_muc_directed_msg_color': [ opt_color, 'red2' ],
-            }, {}),
+
             'contacts': ({
                     'speller_language': [ opt_str, '', _('Language for which misspelled words will be checked')],
             }, {}),
@@ -522,29 +478,6 @@ class Config:
             'muc_message_received': [ False, 'gc_message2.wav', _('Sound to play when any MUC message arrives.') ],
     }
 
-    themes_default = {
-            # sorted alphanum
-            _('default'): [ '', '', '', 'B', '', '', '', 'I', '', '', '', '', '', '',
-                    '', 'B' ],
-
-            _('green'): [ '', '#94aa8c', '', 'B', '#0000ff', '#eff3e7',
-                                    '', 'I', '#000000', '', '', '', '',
-                                    '#94aa8c', '', 'B' ],
-
-            _('grocery'): [ '', '#6bbe18', '', 'B', '#12125a', '#ceefad',
-                                    '', 'I', '#000000', '#efb26b', '', '', '',
-                                    '#108abd', '', 'B' ],
-
-            _('human'): [ '', '#996442', '', 'B', '#ab5920', '#e3ca94',
-                                    '', 'I', '#000000', '', '', '', '',
-                                    '#996442', '', 'B' ],
-
-            _('marine'): [ '', '#918caa', '', 'B', '', '#e9e7f3',
-                                    '', 'I', '#000000', '', '', '', '',
-                                    '#918caa', '', 'B' ],
-
-    }
-
     proxies_default = {
         _('Tor'): ['socks5', 'localhost', 9050],
     }

gajim/common/configpaths.py

@@ -128,6 +128,7 @@ class ConfigPaths:
 
         source_paths = [
             ('DATA', os.path.join(basedir, 'data')),
+            ('STYLE', os.path.join(basedir, 'data', 'style')),
             ('GUI', os.path.join(basedir, 'data', 'gui')),
             ('ICONS', os.path.join(basedir, 'data', 'icons')),
             ('HOME', os.path.expanduser('~')),
@@ -214,6 +215,10 @@ class ConfigPaths:
             # Cache paths
             ('CACHE_DB', 'cache.db', PathLocation.CACHE, PathType.FILE),
             ('AVATAR', 'avatars', PathLocation.CACHE, PathType.FOLDER),
+
+            # Config paths
+            ('MY_THEME', 'theme', PathLocation.CONFIG, PathType.FOLDER),
+
         ]
 
         for path in paths:

gajim/common/connection_handlers_events.py

@@ -1378,3 +1378,11 @@ class InformationEvent(nec.NetworkIncomingEvent):
         else:
             self.args = (self.args,)
         return True
+
+
+class StyleChanged(nec.NetworkIncomingEvent):
+    name = 'style-changed'
+    base_network_events = []
+
+    def generate(self):
+        return True

gajim/common/const.py

-from enum import IntEnum, unique
+from enum import IntEnum, Enum, unique
 from collections import namedtuple
 
 Option = namedtuple('Option', 'kind label type value name callback data desc enabledif props')
 Option.__new__.__defaults__ = (None,) * len(Option._fields)
 
+DialogButton = namedtuple('DialogButton', 'text callback action')
+DialogButton.__new__.__defaults__ = (None, None)
+
 
 @unique
 class OptionKind(IntEnum):
@@ -117,6 +120,24 @@ class JIDConstant(IntEnum):
     NORMAL_TYPE = 0
     ROOM_TYPE = 1
 
+@unique
+class StyleAttr(Enum):
+    COLOR = 'color'
+    BACKGROUND = 'background'
+    FONT = 'font'
+
+@unique
+class CSSPriority(IntEnum):
+    APPLICATION = 600
+    APPLICATION_DARK = 601
+    DEFAULT_THEME = 610
+    DEFAULT_THEME_DARK = 611
+    USER_THEME = 650
+
+@unique
+class ButtonAction(Enum):
+    DESTRUCTIVE = 'destructive-action'
+    SUGGESTED = 'suggested-action'
 
 @unique
 class IdleState(IntEnum):

gajim/common/css_config.py

+# Copyright (C) 2018 Philipp Hörist <philipp AT hoerist.com>
+#
+# This file is part of Gajim.
+#
+# Gajim 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.
+#
+# Gajim 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 Gajim. If not, see <http://www.gnu.org/licenses/>.
+
+import os
+import math
+import logging
+
+import cssutils
+from gi.repository import Gtk
+from gi.repository import Gdk
+from gi.repository import Pango
+
+from gajim.common import app
+from gajim.common import configpaths
+from gajim.common.const import StyleAttr, CSSPriority
+
+log = logging.getLogger('gajim.c.css')
+
+_settings = Gtk.Settings.get_default()
+PREFER_DARK = False
+if _settings is not None:
+    PREFER_DARK = _settings.get_property('gtk-application-prefer-dark-theme')
+
+
+class CSSConfig():
+    def __init__(self):
+        """CSSConfig handles loading and storing of all relevant Gajim style files
+
+        The order in which CSSConfig loads the styles
+
+        1. gajim.css
+        2. gajim-dark.css (Only if gtk-application-prefer-dark-theme = True)
+        3. default.css or default-dark.css (from gajim/data/style)
+        4. user-theme.css (from ~/.config/Gajim/theme)
+
+        # gajim.css:
+
+        This is the main style and the application default
+
+        # gajim-dark.css
+
+        Has only entrys which we want to override in gajim.css
+
+        # default.css or default-dark.css
+
+        Has all the values that are changeable via UI (see themes.py).
+        Depending on `gtk-application-prefer-dark-theme` either default.css or
+        default-dark.css gets loaded
+
+        # user-theme.css
+
+        These are the themes the Themes Dialog stores. Because they are
+        loaded at last they overwrite everything else. Users should add custom
+        css here."""
+
+        # Delete empty rules
+        cssutils.ser.prefs.keepEmptyRules = False
+
+        # Holds the currently selected theme in the Theme Editor
+        self._pre_css = None
+        self._pre_css_path = None
+
+        # Holds the default theme, its used if values are not found
+        # in the selected theme
+        self._default_css = None
+        self._default_css_path = None
+
+        # Holds the currently selected theme
+        self._css = None
+        self._css_path = None
+
+        # User Theme CSS Provider
+        self._provider = Gtk.CssProvider()
+
+        # Cache of recently requested values
+        self._cache = {}
+
+        # Holds all currently available themes
+        self.themes = []
+
+        self._load_css()
+        self._gather_available_themes()
+        self._load_default()
+        self._load_selected()
+        self._activate_theme()
+        Gtk.StyleContext.add_provider_for_screen(
+            Gdk.Screen.get_default(),
+            self._provider,
+            CSSPriority.USER_THEME)
+
+    def _load_css(self):
+        self._load_css_from_file('gajim.css', CSSPriority.APPLICATION)
+        if PREFER_DARK:
+            self._load_css_from_file('gajim-dark.css',
+                                     CSSPriority.APPLICATION_DARK)
+
+        self._load_css_from_file('default.css', CSSPriority.DEFAULT_THEME)
+        if PREFER_DARK:
+            self._load_css_from_file('default-dark.css',
+                                     CSSPriority.DEFAULT_THEME_DARK)
+
+    def _load_css_from_file(self, filename, priority):
+        path = os.path.join(configpaths.get('STYLE'), filename)
+        try:
+            with open(path, "r") as f:
+                css = f.read()
+        except Exception as exc:
+            log.error('Error loading css: %s', exc)
+            return
+        self._activate_css(css, priority)
+
+    def _activate_css(self, css, priority):
+        try:
+            provider = Gtk.CssProvider()
+            provider.load_from_data(bytes(css.encode('utf-8')))
+            Gtk.StyleContext.add_provider_for_screen(Gdk.Screen.get_default(),
+                                                     provider,
+                                                     priority)
+        except Exception:
+            log.exception('Error loading application css')
+
+    @staticmethod
+    def _pango_to_css_weight(number):
+        # Pango allows for weight values between 100 and 1000
+        # CSS allows only full hundred numbers like 100, 200 ..
+        number = int(number)
+        if number < 100:
+            return 100
+        if number > 900:
+            return 900
+        return int(math.ceil(number / 100.0)) * 100
+
+    def _gather_available_themes(self):
+        files = os.listdir(configpaths.get('MY_THEME'))
+        self.themes = [file[:-4] for file in files if file.endswith('.css')]
+        if 'default' in self.themes:
+            # Ignore user created themes that are named 'default'
+            self.themes.remove('default')
+
+    @classmethod
+    def get_theme_path(cls, theme, user=True):
+        if theme == 'default' and PREFER_DARK:
+            theme = 'default-dark'
+
+        if user:
+            return os.path.join(configpaths.get('MY_THEME'), '%s.css' % theme)
+        return os.path.join(configpaths.get('STYLE'), '%s.css' % theme)
+
+    def _determine_theme_path(self):
+        # Gets the path of the currently active theme.
+        # If it does not exist, it falls back to the default theme
+        theme = app.config.get('roster_theme')
+        if theme == 'default':
+            return self.get_theme_path(theme, user=False)
+
+        theme_path = self.get_theme_path(theme)
+        if not theme or not os.path.exists(theme_path):
+            log.warning('Theme %s not found, fallback to default', theme)
+            app.config.set('roster_theme', 'default')
+            log.info('Use Theme: default')
+            return self.get_theme_path('default', user=False)
+        log.info('Use Theme: %s', theme)
+        return theme_path
+
+    def _load_selected(self, new_path=None):
+        if new_path is None:
+            self._css_path = self._determine_theme_path()
+        else:
+            self._css_path = new_path
+        self._css = cssutils.parseFile(self._css_path)
+
+    def _load_default(self):
+        self._default_css_path = self.get_theme_path('default', user=False)
+        self._default_css = cssutils.parseFile(self._default_css_path)
+
+    def _load_pre(self, theme):
+        log.info('Preload theme %s', theme)
+        self._pre_css_path = self.get_theme_path(theme)
+        self._pre_css = cssutils.parseFile(self._pre_css_path)
+
+    def _write(self, pre):
+        path = self._css_path
+        css = self._css
+        if pre:
+            path = self._pre_css_path
+            css = self._pre_css
+        with open(path, 'w', encoding='utf-8') as file:
+            file.write(css.cssText.decode('utf-8'))
+
+        active = self._pre_css_path == self._css_path
+        if not pre or active:
+            self._load_selected()
+            self._activate_theme()
+
+    def set_value(self, selector, attr, value, pre=False):
+        if attr == StyleAttr.FONT:
+            # forward to set_font() for convenience
+            return self.set_font(selector, value, pre)
+
+        if isinstance(attr, StyleAttr):
+            attr = attr.value
+
+        css = self._css
+        if pre:
+            css = self._pre_css
+        for rule in css:
+            if rule.type != rule.STYLE_RULE:
+                continue
+            if rule.selectorText == selector:
+                log.info('Set %s %s %s', selector, attr, value)
+                rule.style[attr] = value
+                if not pre:
+                    self._add_to_cache(selector, attr, value)
+                self._write(pre)
+                return
+
+        # The rule was not found, so we add it to this theme
+        log.info('Set %s %s %s', selector, attr, value)
+        rule = cssutils.css.CSSStyleRule(selectorText=selector)
+        rule.style[attr] = value
+        css.add(rule)
+