diff --git a/Telegram/SourceFiles/data/data_flags.h b/Telegram/SourceFiles/data/data_flags.h
new file mode 100644
index 000000000..6a9520983
--- /dev/null
+++ b/Telegram/SourceFiles/data/data_flags.h
@@ -0,0 +1,88 @@
+//
+// This file is part of Kepka,
+// an unofficial desktop version of Telegram messaging app,
+// see https://github.com/procxx/kepka
+//
+// Kepka 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.
+//
+// It 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.
+//
+// In addition, as a special exception, the copyright holders give permission
+// to link the code of portions of this program with the OpenSSL library.
+//
+// Full license: https://github.com/procxx/kepka/blob/master/LICENSE
+// Copyright (c) 2014-2017 John Preston, https://desktop.telegram.org
+// Copyright (c) 2017- Kepka Contributors, https://github.com/procxx
+//
+#pragma once
+
+
+namespace Data {
+
+template <
+        typename FlagsType,
+        typename FlagsType::Type kEssential = -1>
+class Flags {
+public:
+        struct Change {
+                Change(FlagsType diff, FlagsType value)
+                : diff(diff)
+                , value(value) {
+                }
+                FlagsType diff = 0;
+                FlagsType value = 0;
+        };
+
+        Flags() = default;
+        Flags(FlagsType value) : _value(value) {
+        }
+
+        void set(FlagsType which) {
+                if (auto diff = which ^ _value) {
+                        _value = which;
+                        updated(diff);
+                }
+        }
+        void add(FlagsType which) {
+                if (auto diff = which & ~_value) {
+                        _value |= which;
+                        updated(diff);
+                }
+        }
+        void remove(FlagsType which) {
+                if (auto diff = which & _value) {
+                        _value &= ~which;
+                        updated(diff);
+                }
+        }
+        FlagsType current() const {
+                return _value;
+        }
+//        rpl::producer<Change> changes() const {
+//                return _changes.events();
+//        }
+//        rpl::producer<Change> value() const {
+//                return _changes.events_starting_with({
+//                        FlagsType::from_raw(kEssential),
+//                        _value });
+//        }
+
+private:
+        void updated(FlagsType diff) {
+                if ((diff &= FlagsType::from_raw(kEssential))) {
+                        _changes.fire({ diff, _value });
+                }
+        }
+
+        FlagsType _value = 0;
+        //rpl::event_stream<Change> _changes;
+
+};
+
+} // namespace Data