diff --git a/Telegram/SourceFiles/api/api_chat_invite.cpp b/Telegram/SourceFiles/api/api_chat_invite.cpp
index aa6534fd8..50bdaf4f0 100644
--- a/Telegram/SourceFiles/api/api_chat_invite.cpp
+++ b/Telegram/SourceFiles/api/api_chat_invite.cpp
@@ -116,14 +116,11 @@ void CheckChatInvite(
 		}
 		Core::App().hideMediaView();
 		const auto show = [&](not_null<PeerData*> chat) {
+			const auto way = Window::SectionShow::Way::Forward;
 			if (const auto forum = chat->forum()) {
-				strong->openForum(
-					forum->channel(),
-					Window::SectionShow::Way::Forward);
+				strong->showForum(forum, way);
 			} else {
-				strong->showPeerHistory(
-					chat,
-					Window::SectionShow::Way::Forward);
+				strong->showPeerHistory(chat, way);
 			}
 		};
 		result.match([=](const MTPDchatInvite &data) {
diff --git a/Telegram/SourceFiles/core/application.cpp b/Telegram/SourceFiles/core/application.cpp
index 4719a6870..399196ef6 100644
--- a/Telegram/SourceFiles/core/application.cpp
+++ b/Telegram/SourceFiles/core/application.cpp
@@ -1241,8 +1241,10 @@ void Application::closeChatFromWindows(not_null<PeerData*> peer) {
 				PeerId(0),
 				Window::SectionShow::Way::ClearStack);
 		}
-		if (primary->openedForum().current() == peer) {
-			primary->closeForum();
+		if (const auto forum = primary->shownForum().current()) {
+			if (peer->forum() == forum) {
+				primary->closeForum();
+			}
 		}
 	}
 }
diff --git a/Telegram/SourceFiles/dialogs/dialogs_inner_widget.cpp b/Telegram/SourceFiles/dialogs/dialogs_inner_widget.cpp
index 9a4dd7fe6..4b9b90c40 100644
--- a/Telegram/SourceFiles/dialogs/dialogs_inner_widget.cpp
+++ b/Telegram/SourceFiles/dialogs/dialogs_inner_widget.cpp
@@ -149,6 +149,9 @@ InnerWidget::InnerWidget(
 , _pinnedShiftAnimation([=](crl::time now) {
 	return pinnedShiftAnimationCallback(now);
 })
+, _narrowWidth(st::defaultDialogRow.padding.left()
+	+ st::defaultDialogRow.photoSize
+	+ st::defaultDialogRow.padding.left())
 , _cancelSearchInChat(this, st::dialogsCancelSearchInPeer)
 , _cancelSearchFromUser(this, st::dialogsCancelSearchInPeer) {
 	setAttribute(Qt::WA_OpaquePaintEvent, true);
@@ -487,9 +490,8 @@ void InnerWidget::changeOpenedFolder(Data::Folder *folder) {
 	}
 }
 
-void InnerWidget::changeOpenedForum(ChannelData *forum) {
-	const auto now = _openedForum ? _openedForum->channel().get() : nullptr;
-	if (now == forum) {
+void InnerWidget::changeOpenedForum(Data::Forum *forum) {
+	if (_openedForum == forum) {
 		return;
 	}
 	stopReorderPinned();
@@ -501,19 +503,19 @@ void InnerWidget::changeOpenedForum(ChannelData *forum) {
 	_filterId = forum
 		? 0
 		: _controller->activeChatsFilterCurrent();
-	if (const auto old = now ? now->forum() : nullptr) {
+	if (_openedForum) {
 		// If we close it inside forum destruction we should not schedule.
-		old->owner().forumIcons().scheduleUserpicsReset(old);
+		session().data().forumIcons().scheduleUserpicsReset(_openedForum);
 	}
-	_openedForum = forum ? forum->forum() : nullptr;
+	_openedForum = forum;
 	_st = forum ? &st::forumTopicRow : &st::defaultDialogRow;
 	refreshShownList();
 
 	_openedForumLifetime.destroy();
 	if (forum) {
 		rpl::merge(
-			forum->forum()->chatsListChanges(),
-			forum->forum()->chatsListLoadedEvents()
+			forum->chatsListChanges(),
+			forum->chatsListLoadedEvents()
 		) | rpl::start_with_next([=] {
 			refresh();
 		}, _openedForumLifetime);
@@ -571,7 +573,7 @@ void InnerWidget::paintEvent(QPaintEvent *e) {
 				&& _selectedTopicJump
 				&& (!_pressed || _pressedTopicJump)),
 			.paused = videoPaused,
-			.narrow = (fullWidth < st::columnMinimalWidthLeft),
+			.narrow = (fullWidth < st::columnMinimalWidthLeft / 2),
 		});
 	};
 	if (_state == WidgetState::Default) {
@@ -826,7 +828,7 @@ void InnerWidget::paintEvent(QPaintEvent *e) {
 						.selected = selected,
 						.paused = videoPaused,
 						.search = true,
-						.narrow = (fullWidth < st::columnMinimalWidthLeft),
+						.narrow = (fullWidth < st::columnMinimalWidthLeft / 2),
 						.displayUnreadInfo = showUnreadInSearchResults,
 					});
 					p.translate(0, _st->height);
@@ -896,7 +898,7 @@ void InnerWidget::paintCollapsedRow(
 		.st = _st,
 		.width = fullWidth,
 		.selected = selected,
-		.narrow = (fullWidth < st::columnMinimalWidthLeft),
+		.narrow = (fullWidth < st::columnMinimalWidthLeft / 2),
 	});
 }
 
@@ -1698,7 +1700,9 @@ void InnerWidget::resizeEvent(QResizeEvent *e) {
 }
 
 void InnerWidget::moveCancelSearchButtons() {
-	const auto widthForCancelButton = qMax(width(), st::columnMinimalWidthLeft);
+	const auto widthForCancelButton = qMax(
+		width(),
+		st::columnMinimalWidthLeft - _narrowWidth);
 	const auto left = widthForCancelButton - st::dialogsSearchInSkip - _cancelSearchInChat->width();
 	const auto top = (st::dialogsSearchInHeight - st::dialogsCancelSearchInPeer.height) / 2;
 	_cancelSearchInChat->moveToLeft(left, st::searchedBarHeight + top);
diff --git a/Telegram/SourceFiles/dialogs/dialogs_inner_widget.h b/Telegram/SourceFiles/dialogs/dialogs_inner_widget.h
index 8265b3101..8001b5404 100644
--- a/Telegram/SourceFiles/dialogs/dialogs_inner_widget.h
+++ b/Telegram/SourceFiles/dialogs/dialogs_inner_widget.h
@@ -102,7 +102,7 @@ public:
 	void clearSelection();
 
 	void changeOpenedFolder(Data::Folder *folder);
-	void changeOpenedForum(ChannelData *forum);
+	void changeOpenedForum(Data::Forum *forum);
 	void selectSkip(int32 direction);
 	void selectSkipPage(int32 pixels, int32 direction);
 
@@ -422,6 +422,7 @@ private:
 
 	// Remember the last currently dragged row top shift for updating area.
 	int _aboveTopShift = -1;
+	int _narrowWidth = 0;
 
 	int _visibleTop = 0;
 	int _visibleBottom = 0;
diff --git a/Telegram/SourceFiles/dialogs/dialogs_widget.cpp b/Telegram/SourceFiles/dialogs/dialogs_widget.cpp
index 3bfe85d80..9f7e57cf4 100644
--- a/Telegram/SourceFiles/dialogs/dialogs_widget.cpp
+++ b/Telegram/SourceFiles/dialogs/dialogs_widget.cpp
@@ -178,10 +178,15 @@ void Widget::BottomButton::paintEvent(QPaintEvent *e) {
 
 Widget::Widget(
 	QWidget *parent,
-	not_null<Window::SessionController*> controller)
+	not_null<Window::SessionController*> controller,
+	Layout layout)
 : Window::AbstractSectionWidget(parent, controller, nullptr)
 , _api(&controller->session().mtp())
 , _chooseByDragTimer([=] { _inner->chooseRow(); })
+, _layout(layout)
+, _narrowWidth(st::defaultDialogRow.padding.left()
+	+ st::defaultDialogRow.photoSize
+	+ st::defaultDialogRow.padding.left())
 , _searchControls(this)
 , _mainMenuToggle(_searchControls, st::dialogsMenuToggle)
 , _searchForNarrowFilters(_searchControls, st::dialogsSearchForNarrowFilters)
@@ -216,7 +221,7 @@ Widget::Widget(
 		Data::HistoryUpdate::Flag::MessageSent
 	) | rpl::filter([=](const Data::HistoryUpdate &update) {
 		if (_openedForum) {
-			return (update.history->peer == _openedForum);
+			return (update.history == _openedForum->history());
 		} else if (_openedFolder) {
 			return (update.history->folder() == _openedFolder)
 				&& !update.history->isPinnedDialog(FilterId());
@@ -273,7 +278,7 @@ Widget::Widget(
 	_inner->cancelSearchFromUserRequests(
 	) | rpl::start_with_next([=] {
 		setSearchInChat((_openedForum && !_searchInChat)
-			? Key(_openedForum->forum()->history())
+			? Key(_openedForum->history())
 			: _searchInChat, nullptr);
 		applyFilterUpdate(true);
 	}, lifetime());
@@ -346,7 +351,10 @@ Widget::Widget(
 	setupShortcuts();
 
 	_searchForNarrowFilters->setClickedCallback([=] {
-		Ui::showChatsList(&session());
+		if (_childList) {
+			controller->closeForum();
+		}
+		_filter->setFocus();
 	});
 
 	setAcceptDrops(true);
@@ -368,7 +376,7 @@ Widget::Widget(
 					&& !_searchFullMigrated))) {
 			searchMore();
 		} else if (_openedForum && state == WidgetState::Default) {
-			_openedForum->forum()->requestTopics();
+			_openedForum->requestTopics();
 		} else {
 			const auto folder = _inner->shownFolder();
 			if (!folder || !folder->chatsList()->loaded()) {
@@ -399,14 +407,19 @@ Widget::Widget(
 		changeOpenedFolder(folder, anim::type::normal);
 	}, lifetime());
 
-	changeOpenedForum(
-		controller->openedForum().current(),
-		anim::type::instant);
-
-	controller->openedForum().changes(
-	) | rpl::start_with_next([=](ChannelData *forum) {
-		changeOpenedForum(forum, anim::type::normal);
-	}, lifetime());
+	if (_layout != Layout::Child) {
+		controller->shownForum().changes(
+		) | rpl::filter(!rpl::mappers::_1) | rpl::start_with_next([=] {
+			if (_openedForum) {
+				changeOpenedForum(nullptr, anim::type::normal);
+			} else if (_childList) {
+				_childList = nullptr;
+				_childListShadow = nullptr;
+				updateControlsGeometry();
+				updateControlsVisibility(true);
+			}
+		}, lifetime());
+	}
 
 	setupDownloadBar();
 }
@@ -420,7 +433,9 @@ void Widget::chosenRow(const ChosenRow &row) {
 		: nullptr;
 	if (topicJump) {
 		if (!controller()->adaptive().isOneColumn()) {
-			controller()->openForum(history->peer->asChannel());
+			controller()->showForum(
+				topicJump->forum(),
+				Window::SectionShow().withChildColumn());
 		}
 		controller()->content()->chooseThread(
 			topicJump,
@@ -431,7 +446,9 @@ void Widget::chosenRow(const ChosenRow &row) {
 			topic,
 			row.message.fullId.msg);
 	} else if (history && history->peer->isForum() && !row.message.fullId) {
-		controller()->openForum(history->peer->asChannel());
+		controller()->showForum(
+			history->peer->forum(),
+			Window::SectionShow().withChildColumn());
 		return;
 	} else if (history) {
 		const auto peer = history->peer;
@@ -450,19 +467,18 @@ void Widget::chosenRow(const ChosenRow &row) {
 			};
 			if (fromActive) {
 				controller()->window().preventOrInvoke([=] {
-					controller()->content()->ui_showPeerHistory(
-						0,
-						Window::SectionShow::Way::ClearStack,
-						0);
+					controller()->clearSectionStack();
 					toSeparate();
 				});
 			} else {
 				toSeparate();
 			}
 		} else {
+			hideChildList();
 			controller()->content()->chooseThread(history, showAtMsgId);
 		}
 	} else if (const auto folder = row.key.folder()) {
+		hideChildList();
 		controller()->openFolder(folder);
 	}
 	if (openSearchResult && !session().supportMode()) {
@@ -576,7 +592,8 @@ void Widget::updateScrollUpVisibility() {
 }
 
 void Widget::startScrollUpButtonAnimation(bool shown) {
-	const auto smallColumn = (width() < st::columnMinimalWidthLeft);
+	const auto smallColumn = (width() < st::columnMinimalWidthLeft)
+		|| _childList;
 	shown &= !smallColumn;
 	if (_scrollToTopIsShown == shown) {
 		return;
@@ -659,7 +676,7 @@ void Widget::setupShortcuts() {
 		}
 		if (_openedForum && !controller()->activeChatCurrent()) {
 			request->check(Command::Search) && request->handle([=] {
-				const auto history = _openedForum->forum()->history();
+				const auto history = _openedForum->history();
 				controller()->content()->searchInChat(history);
 				return true;
 			});
@@ -723,6 +740,10 @@ void Widget::updateControlsVisibility(bool fast) {
 		updateSearchFromVisibility(fast);
 	}
 	_connecting->setForceHidden(false);
+	if (_childList) {
+		_childList->show();
+		_childListShadow->show();
+	}
 }
 
 void Widget::changeOpenedSubsection(
@@ -761,7 +782,7 @@ void Widget::changeOpenedFolder(Data::Folder *folder, anim::type animated) {
 	}, (folder != nullptr), animated);
 }
 
-void Widget::changeOpenedForum(ChannelData *forum, anim::type animated) {
+void Widget::changeOpenedForum(Data::Forum *forum, anim::type animated) {
 	changeOpenedSubsection([&] {
 		cancelSearch();
 		_openedForum = forum;
@@ -770,6 +791,12 @@ void Widget::changeOpenedForum(ChannelData *forum, anim::type animated) {
 	}, (forum != nullptr), animated);
 }
 
+void Widget::hideChildList() {
+	if (_childList) {
+		controller()->closeForum();
+	}
+}
+
 void Widget::refreshTopBars() {
 	if (_openedFolder || _openedForum) {
 		if (!_subsectionTopBar) {
@@ -797,7 +824,7 @@ void Widget::refreshTopBars() {
 			updateControlsGeometry();
 		}
 		const auto history = _openedForum
-			? session().data().history(_openedForum).get()
+			? _openedForum->history().get()
 			: nullptr;
 		_subsectionTopBar->setActiveChat(
 			HistoryView::TopBarWidget::ActiveChat{
@@ -817,23 +844,24 @@ void Widget::refreshTopBars() {
 	}
 	_forumSearchRequested = false;
 	if (_openedForum) {
-		_openedForum->updateFull();
+		const auto channel = _openedForum->channel();
+		channel->updateFull();
 
 		_forumReportBar = std::make_unique<HistoryView::ContactStatus>(
 			controller(),
 			this,
-			_openedForum,
+			channel,
 			true);
 		_forumRequestsBar = std::make_unique<Ui::RequestsBar>(
 			this,
 			HistoryView::RequestsBarContentByPeer(
-				_openedForum,
+				channel,
 				st::historyRequestsUserpics.size,
 				true));
 		_forumGroupCallBar = std::make_unique<Ui::GroupCallBar>(
 			this,
 			HistoryView::GroupCallBarContentByPeer(
-				_openedForum,
+				channel,
 				st::historyGroupCallUserpics.size,
 				true),
 			Core::App().appDeactivatedValue());
@@ -841,15 +869,15 @@ void Widget::refreshTopBars() {
 
 		_forumRequestsBar->barClicks(
 		) | rpl::start_with_next([=] {
-			RequestsBoxController::Start(controller(), _openedForum);
+			RequestsBoxController::Start(controller(), channel);
 		}, _forumRequestsBar->lifetime());
 
 		rpl::merge(
 			_forumGroupCallBar->barClicks(),
 			_forumGroupCallBar->joinClicks()
 		) | rpl::start_with_next([=] {
-			if (_openedForum->groupCall()) {
-				controller()->startOrJoinGroupCall(_openedForum);
+			if (channel->groupCall()) {
+				controller()->startOrJoinGroupCall(channel);
 			}
 		}, _forumGroupCallBar->lifetime());
 
@@ -959,7 +987,7 @@ void Widget::jumpToTop(bool belowPinned) {
 		auto to = 0;
 		if (belowPinned) {
 			const auto list = _openedForum
-				? _openedForum->forum()->topicsList()
+				? _openedForum->topicsList()
 				: controller()->activeChatsFilterCurrent()
 				? session().data().chatsFilters().chatsList(
 					controller()->activeChatsFilterCurrent())
@@ -1113,7 +1141,7 @@ void Widget::animationCallback() {
 
 void Widget::escape() {
 	if (!cancelSearch()) {
-		if (controller()->openedForum().current()) {
+		if (controller()->shownForum().current()) {
 			controller()->closeForum();
 		} else if (controller()->openedFolder().current()) {
 			controller()->closeFolder();
@@ -1351,7 +1379,7 @@ bool Widget::searchForTopicsRequired(const QString &query) const {
 		&& _openedForum
 		&& !query.isEmpty()
 		&& (query[0] != '#')
-		&& !_openedForum->forum()->topicsList()->loaded();
+		&& !_openedForum->topicsList()->loaded();
 }
 
 void Widget::needSearchMessages() {
@@ -1370,7 +1398,7 @@ void Widget::searchMessages(
 	const auto inChatChanged = [&] {
 		const auto inPeer = inChat.peer();
 		const auto inTopic = inChat.topic();
-		if (!inTopic && inPeer == _openedForum) {
+		if (!inTopic && _openedForum && inPeer == _openedForum->channel()) {
 			return false;
 		} else if ((inTopic || (inPeer && !inPeer->isForum()))
 			&& (inChat == _searchInChat)) {
@@ -1404,7 +1432,7 @@ void Widget::searchTopics() {
 	_api.request(base::take(_topicSearchRequest)).cancel();
 	_topicSearchRequest = _api.request(MTPchannels_GetForumTopics(
 		MTP_flags(MTPchannels_GetForumTopics::Flag::f_q),
-		_openedForum->inputChannel,
+		_openedForum->channel()->inputChannel,
 		MTP_string(_topicSearchQuery),
 		MTP_int(_topicSearchOffsetDate),
 		MTP_int(_topicSearchOffsetId),
@@ -1414,7 +1442,7 @@ void Widget::searchTopics() {
 		_topicSearchRequest = 0;
 		const auto savedTopicId = _topicSearchOffsetTopicId;
 		const auto byCreation = result.data().is_order_by_create_date();
-		_openedForum->forum()->applyReceivedTopics(result, [&](
+		_openedForum->applyReceivedTopics(result, [&](
 				not_null<Data::ForumTopic*> topic) {
 			_topicSearchOffsetTopicId = topic->rootId();
 			if (byCreation) {
@@ -1826,6 +1854,9 @@ void Widget::dropEvent(QDropEvent *e) {
 		const auto point = mapToGlobal(e->pos());
 		if (const auto thread = _inner->updateFromParentDrag(point)) {
 			e->acceptProposedAction();
+			if (!thread->owningHistory()->peer->isForum()) {
+				hideChildList();
+			}
 			controller()->content()->onFilesOrForwardDrop(
 				thread,
 				e->mimeData());
@@ -1877,6 +1908,39 @@ void Widget::applyFilterUpdate(bool force) {
 	_lastFilterText = filterText;
 }
 
+void Widget::showForum(
+		not_null<Data::Forum*> forum,
+		const Window::SectionShow &params) {
+	if (!params.childColumn
+		|| !Core::App().settings().dialogsWidthRatio()
+		|| (_layout != Layout::Main)) {
+		changeOpenedForum(forum, params.animated);
+		return;
+	}
+	cancelSearch();
+	auto copy = params;
+	copy.childColumn = false;
+	copy.animated = anim::type::instant;
+	_childList = std::make_unique<Widget>(
+		this,
+		controller(),
+		Layout::Child);
+	_childList->showForum(forum, copy);
+	_childListShadow = std::make_unique<Ui::RpWidget>(this);
+	_childListShadow->setAttribute(Qt::WA_TransparentForMouseEvents);
+	_childListShadow->paintRequest(
+	) | rpl::start_with_next([=] {
+		auto p = QPainter(_childListShadow.get());
+		st::slideShadow.fill(p, QRect(
+			_childListShadow->width() - st::slideShadow.width(),
+			0,
+			st::slideShadow.width(),
+			_childListShadow->height()));
+	}, _childListShadow->lifetime());
+	updateControlsGeometry();
+	updateControlsVisibility(true);
+}
+
 void Widget::searchInChat(Key chat) {
 	if (_openedForum && !chat.peer()->forum()) {
 		controller()->closeForum();
@@ -1889,7 +1953,13 @@ void Widget::searchInChat(Key chat) {
 	applyFilterUpdate(true);
 }
 
-void Widget::setSearchInChat(Key chat, PeerData *from) {
+bool Widget::setSearchInChat(Key chat, PeerData *from) {
+	if (_childList) {
+		if (_childList->setSearchInChat(chat, from)) {
+			return true;
+		}
+		hideChildList();
+	}
 	const auto peer = chat.peer();
 	const auto topic = chat.topic();
 	const auto forum = peer ? peer->forum() : nullptr;
@@ -1907,11 +1977,13 @@ void Widget::setSearchInChat(Key chat, PeerData *from) {
 	_searchFromAuthor = from;
 
 	if (forum) {
-		if (controller()->openedForum().current() == peer) {
+		if (_openedForum == forum) {
 			showSearchInTopBar(anim::type::normal);
-		} else {
+		} else if (_layout == Layout::Main) {
 			_forumSearchRequested = true;
-			controller()->openForum(forum->channel());
+			controller()->showForum(forum);
+		} else {
+			return false;
 		}
 	}
 	_searchInMigrated = nullptr;
@@ -1943,6 +2015,7 @@ void Widget::setSearchInChat(Key chat, PeerData *from) {
 		cancelSearch();
 	}
 	_filter->setFocus();
+	return true;
 }
 
 void Widget::clearSearchCache() {
@@ -1971,7 +2044,7 @@ void Widget::showSearchFrom() {
 	if (const auto peer = searchInPeer()) {
 		const auto weak = base::make_weak(_searchInChat.topic());
 		const auto chat = (!_searchInChat && _openedForum)
-			? Key(_openedForum->forum()->history())
+			? Key(_openedForum->history())
 			: _searchInChat;
 		auto box = SearchFromBox(
 			peer,
@@ -2107,25 +2180,37 @@ void Widget::updateControlsGeometry() {
 		_forwardCancel->moveToLeft(0, filterAreaTop);
 		filterAreaTop += st::dialogsForwardHeight;
 	}
-	auto smallLayoutWidth = (st::defaultDialogRow.padding.left() + st::defaultDialogRow.photoSize + st::defaultDialogRow.padding.left());
-	auto smallLayoutRatio = (width() < st::columnMinimalWidthLeft) ? (st::columnMinimalWidthLeft - width()) / float64(st::columnMinimalWidthLeft - smallLayoutWidth) : 0.;
-	auto filterLeft = (controller()->filtersWidth() ? st::dialogsFilterSkip : st::dialogsFilterPadding.x() + _mainMenuToggle->width()) + st::dialogsFilterPadding.x();
-	auto filterRight = (session().domain().local().hasLocalPasscode() ? (st::dialogsFilterPadding.x() + _lockUnlock->width()) : st::dialogsFilterSkip) + st::dialogsFilterPadding.x();
-	auto filterWidth = qMax(width(), st::columnMinimalWidthLeft) - filterLeft - filterRight;
+	const auto usew = _childList ? _narrowWidth : width();
+	const auto childw = std::max(_narrowWidth, width() - usew);
+	const auto smallw = st::columnMinimalWidthLeft - _narrowWidth;
+	const auto smallLayoutRatio = (usew < smallw)
+		? ((smallw - usew) / float64(smallw - _narrowWidth))
+		: 0.;
+	auto filterLeft = (controller()->filtersWidth()
+		? st::dialogsFilterSkip
+		: (st::dialogsFilterPadding.x() + _mainMenuToggle->width()))
+		+ st::dialogsFilterPadding.x();
+	auto filterRight = (session().domain().local().hasLocalPasscode()
+		? (st::dialogsFilterPadding.x() + _lockUnlock->width())
+		: st::dialogsFilterSkip) + st::dialogsFilterPadding.x();
+	auto filterWidth = qMax(usew, smallw) - filterLeft - filterRight;
 	auto filterAreaHeight = st::topBarHeight;
-	_searchControls->setGeometry(0, filterAreaTop, width(), filterAreaHeight);
+	_searchControls->setGeometry(0, filterAreaTop, usew, filterAreaHeight);
 	if (_subsectionTopBar) {
 		_subsectionTopBar->setGeometry(_searchControls->geometry());
 	}
 
 	auto filterTop = (filterAreaHeight - _filter->height()) / 2;
-	filterLeft = anim::interpolate(filterLeft, smallLayoutWidth, smallLayoutRatio);
+	filterLeft = anim::interpolate(filterLeft, _narrowWidth, smallLayoutRatio);
 	_filter->setGeometryToLeft(filterLeft, filterTop, filterWidth, _filter->height());
-	auto mainMenuLeft = anim::interpolate(st::dialogsFilterPadding.x(), (smallLayoutWidth - _mainMenuToggle->width()) / 2, smallLayoutRatio);
+	auto mainMenuLeft = anim::interpolate(
+		st::dialogsFilterPadding.x(),
+		(_narrowWidth - _mainMenuToggle->width()) / 2,
+		smallLayoutRatio);
 	_mainMenuToggle->moveToLeft(mainMenuLeft, st::dialogsFilterPadding.y());
 	const auto searchLeft = anim::interpolate(
 		-_searchForNarrowFilters->width(),
-		(smallLayoutWidth - _searchForNarrowFilters->width()) / 2,
+		(_narrowWidth - _searchForNarrowFilters->width()) / 2,
 		smallLayoutRatio);
 	_searchForNarrowFilters->moveToLeft(searchLeft, st::dialogsFilterPadding.y());
 
@@ -2139,19 +2224,19 @@ void Widget::updateControlsGeometry() {
 		_forumTopShadow->setGeometry(
 			0,
 			filterAreaTop + filterAreaHeight,
-			width(),
+			usew,
 			st::lineWidth);
 	}
 	const auto forumGroupCallTop = filterAreaTop + filterAreaHeight;
 	if (_forumGroupCallBar) {
 		_forumGroupCallBar->move(0, forumGroupCallTop);
-		_forumGroupCallBar->resizeToWidth(width());
+		_forumGroupCallBar->resizeToWidth(usew);
 	}
 	const auto forumRequestsTop = forumGroupCallTop
 		+ (_forumGroupCallBar ? _forumGroupCallBar->height() : 0);
 	if (_forumRequestsBar) {
 		_forumRequestsBar->move(0, forumRequestsTop);
-		_forumRequestsBar->resizeToWidth(width());
+		_forumRequestsBar->resizeToWidth(usew);
 	}
 	const auto forumReportTop = forumRequestsTop
 		+ (_forumRequestsBar ? _forumRequestsBar->height() : 0);
@@ -2169,7 +2254,7 @@ void Widget::updateControlsGeometry() {
 			button->setGeometry(
 				0,
 				scrollTop + scrollHeight,
-				width(),
+				usew,
 				buttonHeight);
 		}
 	};
@@ -2182,8 +2267,8 @@ void Widget::updateControlsGeometry() {
 	}
 	controller()->setConnectingBottomSkip(bottomSkip);
 	auto wasScrollHeight = _scroll->height();
-	_scroll->setGeometry(0, scrollTop, width(), scrollHeight);
-	_inner->resize(width(), _inner->height());
+	_scroll->setGeometry(0, scrollTop, usew, scrollHeight);
+	_inner->resize(usew, _inner->height());
 	if (scrollHeight != wasScrollHeight) {
 		controller()->floatPlayerAreaUpdated();
 	}
@@ -2195,6 +2280,13 @@ void Widget::updateControlsGeometry() {
 	if (_scrollToTopIsShown) {
 		updateScrollUpPosition();
 	}
+
+	if (_childList) {
+		_childList->setGeometryWithTopMoved(
+			{ width() - childw, 0, childw, height() },
+			_topDelta);
+		_childListShadow->setGeometry(0, 0, (width() - childw), height());
+	}
 }
 
 rpl::producer<> Widget::closeForwardBarRequests() const {
@@ -2322,7 +2414,9 @@ void Widget::cancelSearchRequest() {
 }
 
 PeerData *Widget::searchInPeer() const {
-	return _openedForum ? _openedForum : _searchInChat.peer();
+	return _openedForum
+		? _openedForum->channel().get()
+		: _searchInChat.peer();
 }
 
 Data::ForumTopic *Widget::searchInTopic() const {
diff --git a/Telegram/SourceFiles/dialogs/dialogs_widget.h b/Telegram/SourceFiles/dialogs/dialogs_widget.h
index e92338bcd..f51ceb9c5 100644
--- a/Telegram/SourceFiles/dialogs/dialogs_widget.h
+++ b/Telegram/SourceFiles/dialogs/dialogs_widget.h
@@ -20,6 +20,10 @@ namespace MTP {
 class Error;
 } // namespace MTP
 
+namespace Data {
+class Forum;
+} // namespace Data
+
 namespace Main {
 class Session;
 } // namespace Main
@@ -47,6 +51,7 @@ class FadeWrapScaled;
 namespace Window {
 class SessionController;
 class ConnectionState;
+struct SectionShow;
 } // namespace Window
 
 namespace Dialogs {
@@ -61,7 +66,14 @@ enum class SearchRequestType;
 
 class Widget final : public Window::AbstractSectionWidget {
 public:
-	Widget(QWidget *parent, not_null<Window::SessionController*> controller);
+	enum class Layout {
+		Main,
+		Child,
+	};
+	Widget(
+		QWidget *parent,
+		not_null<Window::SessionController*> controller,
+		Layout layout);
 
 	// When resizing the widget with top edge moved up or down and we
 	// want to add this top movement to the scroll position, so inner
@@ -70,6 +82,9 @@ public:
 
 	void updateDragInScroll(bool inScroll);
 
+	void showForum(
+		not_null<Data::Forum*> forum,
+		const Window::SectionShow &params);
 	void searchInChat(Key chat);
 	void setInnerFocus();
 
@@ -81,7 +96,9 @@ public:
 	bool hasTopBarShadow() const {
 		return true;
 	}
-	void showAnimated(Window::SlideDirection direction, const Window::SectionSlideParams &params);
+	void showAnimated(
+		Window::SlideDirection direction,
+		const Window::SectionSlideParams &params);
 	void showFast();
 
 	void scrollToEntry(const RowDescriptor &entry);
@@ -152,7 +169,7 @@ private:
 	void setupShortcuts();
 	[[nodiscard]] bool searchForPeersRequired(const QString &query) const;
 	[[nodiscard]] bool searchForTopicsRequired(const QString &query) const;
-	void setSearchInChat(Key chat, PeerData *from = nullptr);
+	bool setSearchInChat(Key chat, PeerData *from = nullptr);
 	void showCalendar();
 	void showSearchFrom();
 	void showMainMenu();
@@ -171,8 +188,9 @@ private:
 		bool fromRight,
 		anim::type animated);
 	void changeOpenedFolder(Data::Folder *folder, anim::type animated);
-	void changeOpenedForum(ChannelData *forum, anim::type animated);
-	QPixmap grabForFolderSlideAnimation();
+	void changeOpenedForum(Data::Forum *forum, anim::type animated);
+	void hideChildList();
+	[[nodiscard]] QPixmap grabForFolderSlideAnimation();
 	void startSlideAnimation();
 
 	void fullSearchRefreshOn(rpl::producer<> events);
@@ -198,6 +216,8 @@ private:
 	bool _dragForward = false;
 	base::Timer _chooseByDragTimer;
 
+	Layout _layout = Layout::Main;
+	int _narrowWidth = 0;
 	object_ptr<Ui::IconButton> _forwardCancel = { nullptr };
 	object_ptr<Ui::RpWidget> _searchControls;
 	object_ptr<HistoryView::TopBarWidget> _subsectionTopBar = { nullptr } ;
@@ -234,7 +254,7 @@ private:
 	bool _forumSearchRequested = false;
 
 	Data::Folder *_openedFolder = nullptr;
-	ChannelData *_openedForum = nullptr;
+	Data::Forum *_openedForum = nullptr;
 	Dialogs::Key _searchInChat;
 	History *_searchInMigrated = nullptr;
 	PeerData *_searchFromAuthor = nullptr;
@@ -277,6 +297,9 @@ private:
 
 	rpl::event_stream<> _closeForwardBarRequests;
 
+	std::unique_ptr<Widget> _childList;
+	std::unique_ptr<Ui::RpWidget> _childListShadow;
+
 };
 
 } // namespace Dialogs
diff --git a/Telegram/SourceFiles/facades.cpp b/Telegram/SourceFiles/facades.cpp
index 21b7c13c4..5c3b43915 100644
--- a/Telegram/SourceFiles/facades.cpp
+++ b/Telegram/SourceFiles/facades.cpp
@@ -35,46 +35,27 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "data/data_session.h"
 #include "styles/style_chat.h"
 
-namespace {
-
-[[nodiscard]] MainWidget *CheckMainWidget(not_null<Main::Session*> session) {
-	if (const auto m = App::main()) { // multi good
-		if (&m->session() == session) {
-			return m;
-		}
-	}
-	if (&Core::App().domain().active() != &session->account()) {
-		Core::App().domain().activate(&session->account());
-	}
-	if (const auto m = App::main()) { // multi good
-		if (&m->session() == session) {
-			return m;
-		}
-	}
-	return nullptr;
-}
-
-} // namespace
-
 namespace Ui {
 
 void showChatsList(not_null<Main::Session*> session) {
-	if (const auto m = CheckMainWidget(session)) {
-		m->ui_showPeerHistory(
-			0,
-			::Window::SectionShow::Way::ClearStack,
-			0);
+	if (const auto window = session->tryResolveWindow()) {
+		window->clearSectionStack();
 	}
 }
 
-void showPeerHistory(not_null<const History*> history, MsgId msgId) {
-	showPeerHistory(history->peer, msgId);
+void showPeerHistory(not_null<History*> history, MsgId msgId) {
+	if (const auto window = history->session().tryResolveWindow()) {
+		window->showPeerHistory(
+			history,
+			::Window::SectionShow::Way::ClearStack,
+			msgId);
+	}
 }
 
-void showPeerHistory(not_null<const PeerData*> peer, MsgId msgId) {
-	if (const auto m = CheckMainWidget(&peer->session())) {
-		m->ui_showPeerHistory(
-			peer->id,
+void showPeerHistory(not_null<PeerData*> peer, MsgId msgId) {
+	if (const auto window = peer->session().tryResolveWindow()) {
+		window->showPeerHistory(
+			peer,
 			::Window::SectionShow::Way::ClearStack,
 			msgId);
 	}
diff --git a/Telegram/SourceFiles/facades.h b/Telegram/SourceFiles/facades.h
index 10c0e7fb4..1dee53a40 100644
--- a/Telegram/SourceFiles/facades.h
+++ b/Telegram/SourceFiles/facades.h
@@ -40,8 +40,8 @@ namespace Ui {
 
 // Legacy global methods.
 
-void showPeerHistory(not_null<const PeerData*> peer, MsgId msgId);
-void showPeerHistory(not_null<const History*> history, MsgId msgId);
+void showPeerHistory(not_null<PeerData*> peer, MsgId msgId);
+void showPeerHistory(not_null<History*> history, MsgId msgId);
 void showChatsList(not_null<Main::Session*> session);
 
 bool skipPaintEvent(QWidget *widget, QPaintEvent *event);
diff --git a/Telegram/SourceFiles/info/profile/info_profile_actions.cpp b/Telegram/SourceFiles/info/profile/info_profile_actions.cpp
index 35f69c44c..51f2c5ab4 100644
--- a/Telegram/SourceFiles/info/profile/info_profile_actions.cpp
+++ b/Telegram/SourceFiles/info/profile/info_profile_actions.cpp
@@ -633,16 +633,16 @@ Ui::MultiSlideTracker DetailsFiller::fillTopicButtons() {
 	Ui::MultiSlideTracker tracker;
 	const auto window = _controller->parentController();
 
-	const auto channel = _topic->channel().get();
+	const auto forum = _topic->forum();
 	auto showTopicsVisible = rpl::combine(
 		window->adaptive().oneColumnValue(),
-		window->openedForum().value(),
-		_1 || (_2 != channel));
+		window->shownForum().value(),
+		_1 || (_2 != forum));
 	AddMainButton(
 		_wrap,
 		tr::lng_forum_show_topics_list(),
 		std::move(showTopicsVisible),
-		[=] { window->openForum(channel); },
+		[=] { window->showForum(forum); },
 		tracker);
 	return tracker;
 }
diff --git a/Telegram/SourceFiles/main/main_session.cpp b/Telegram/SourceFiles/main/main_session.cpp
index 80be9b409..3b95165bd 100644
--- a/Telegram/SourceFiles/main/main_session.cpp
+++ b/Telegram/SourceFiles/main/main_session.cpp
@@ -466,6 +466,11 @@ Window::SessionController *Session::tryResolveWindow() const {
 			return nullptr;
 		}
 	}
+	for (const auto &window : _windows) {
+		if (window->isPrimary()) {
+			return window;
+		}
+	}
 	return _windows.front();
 }
 
diff --git a/Telegram/SourceFiles/mainwidget.cpp b/Telegram/SourceFiles/mainwidget.cpp
index 26c2d88a3..b2c3d843c 100644
--- a/Telegram/SourceFiles/mainwidget.cpp
+++ b/Telegram/SourceFiles/mainwidget.cpp
@@ -242,7 +242,10 @@ MainWidget::MainWidget(
 	? base::make_unique_q<Ui::PlainShadow>(this)
 	: nullptr)
 , _dialogs(isPrimary()
-	? base::make_unique_q<Dialogs::Widget>(this, _controller)
+	? base::make_unique_q<Dialogs::Widget>(
+		this,
+		_controller,
+		Dialogs::Widget::Layout::Main)
 	: nullptr)
 , _history(std::in_place, this, _controller)
 , _playerPlaylist(this, _controller)
@@ -612,12 +615,12 @@ bool MainWidget::sendPaths(not_null<Data::Thread*> thread) {
 		Ui::show(Ui::MakeInformBox(*error));
 		return false;
 	} else {
-		controller()->showThread(
+		_controller->showThread(
 			thread,
 			ShowAtTheEndMsgId,
 			Window::SectionShow::Way::ClearStack);
 	}
-	return (controller()->activeChatCurrent().thread() == thread)
+	return (_controller->activeChatCurrent().thread() == thread)
 		&& (_mainSection
 			? _mainSection->confirmSendingFiles(cSendPaths())
 			: _history->confirmSendingFiles(cSendPaths()));
@@ -655,11 +658,11 @@ bool MainWidget::onFilesOrForwardDrop(
 		Ui::show(Ui::MakeInformBox(tr::lng_forward_send_files_cant()));
 		return false;
 	} else {
-		controller()->showThread(
+		_controller->showThread(
 			thread,
 			ShowAtTheEndMsgId,
 			Window::SectionShow::Way::ClearStack);
-		if (controller()->activeChatCurrent().thread() != thread) {
+		if (_controller->activeChatCurrent().thread() != thread) {
 			return false;
 		}
 		(_mainSection
@@ -678,7 +681,7 @@ void MainWidget::clearHider(not_null<Window::HistoryHider*> instance) {
 		return;
 	}
 	_hider.release();
-	controller()->setSelectingPeer(false);
+	_controller->setSelectingPeer(false);
 
 	Assert(_dialogs != nullptr);
 	if (isOneColumn()) {
@@ -703,12 +706,12 @@ void MainWidget::clearHider(not_null<Window::HistoryHider*> instance) {
 }
 
 void MainWidget::hiderLayer(base::unique_qptr<Window::HistoryHider> hider) {
-	if (!_dialogs || controller()->window().locked()) {
+	if (!_dialogs || _controller->window().locked()) {
 		return;
 	}
 
 	_hider = std::move(hider);
-	controller()->setSelectingPeer(true);
+	_controller->setSelectingPeer(true);
 
 	_dialogs->closeForwardBarRequests(
 	) | rpl::start_with_next([=] {
@@ -812,7 +815,7 @@ void MainWidget::clearSelectingPeer() {
 	if (_hider) {
 		_hider->startHide();
 		_hider.release();
-		controller()->setSelectingPeer(false);
+		_controller->setSelectingPeer(false);
 	}
 }
 
@@ -821,8 +824,8 @@ void MainWidget::sendBotCommand(Bot::SendCommandRequest request) {
 		? _mainSection->sendBotCommand(request)
 		: Window::SectionActionResult::Fallback;
 	if (type == Window::SectionActionResult::Fallback) {
-		ui_showPeerHistory(
-			request.peer->id,
+		_controller->showPeerHistory(
+			request.peer,
 			SectionShow::Way::Forward,
 			ShowAtTheEndMsgId);
 		_history->sendBotCommand(request);
@@ -1275,7 +1278,7 @@ void MainWidget::chooseThread(
 	if (selectingPeer()) {
 		_hider->offerThread(thread);
 	} else {
-		controller()->showThread(
+		_controller->showThread(
 			thread,
 			showAtMsgId,
 			Window::SectionShow::Way::ClearStack);
@@ -1301,8 +1304,8 @@ void MainWidget::showChooseReportMessages(
 		Ui::ReportReason reason,
 		Fn<void(MessageIdsList)> done) {
 	_history->setChooseReportMessagesDetails(reason, std::move(done));
-	ui_showPeerHistory(
-		peer->id,
+	_controller->showPeerHistory(
+		peer,
 		SectionShow::Way::Forward,
 		ShowForChooseMessagesMsgId);
 	Ui::ShowMultilineToast({
@@ -1325,7 +1328,7 @@ bool MainWidget::showHistoryInDifferentWindow(
 		MsgId showAtMsgId) {
 	const auto peer = session().data().peer(peerId);
 	if (const auto separate = Core::App().separateWindowForPeer(peer)) {
-		if (separate == &controller()->window()) {
+		if (separate == &_controller->window()) {
 			return false;
 		}
 		separate->sessionController()->showPeerHistory(
@@ -1351,7 +1354,7 @@ bool MainWidget::showHistoryInDifferentWindow(
 	return true;
 }
 
-void MainWidget::ui_showPeerHistory(
+void MainWidget::showPeerHistory(
 		PeerId peerId,
 		const SectionShow &params,
 		MsgId showAtMsgId) {
@@ -1367,7 +1370,7 @@ void MainWidget::ui_showPeerHistory(
 		if (!unavailable.isEmpty()) {
 			Assert(isPrimary());
 			if (params.activation != anim::activation::background) {
-				controller()->show(Ui::MakeInformBox(unavailable));
+				_controller->show(Ui::MakeInformBox(unavailable));
 			}
 			return;
 		}
@@ -1383,7 +1386,7 @@ void MainWidget::ui_showPeerHistory(
 
 	if (!(_history->peer() && _history->peer()->id == peerId)
 		&& preventsCloseSection(
-			[=] { ui_showPeerHistory(peerId, params, showAtMsgId); },
+			[=] { showPeerHistory(peerId, params, showAtMsgId); },
 			params)) {
 		return;
 	}
@@ -1435,7 +1438,7 @@ void MainWidget::ui_showPeerHistory(
 
 	const auto wasActivePeer = _controller->activeChatCurrent().peer();
 	if (params.activation != anim::activation::background) {
-		controller()->window().hideSettingsAndLayer();
+		_controller->window().hideSettingsAndLayer();
 	}
 
 	auto animatedShow = [&] {
@@ -1484,7 +1487,7 @@ void MainWidget::ui_showPeerHistory(
 
 	if (noPeer) {
 		_controller->setActiveChatEntry(Dialogs::Key());
-		_controller->setChatStyleTheme(controller()->defaultChatTheme());
+		_controller->setChatStyleTheme(_controller->defaultChatTheme());
 	}
 
 	if (onlyDialogs) {
@@ -1547,7 +1550,7 @@ void MainWidget::showMessage(
 				return;
 			}
 		} else if (_history->peer() == item->history()->peer) {
-			ui_showPeerHistory(peerId, params, itemId);
+			showPeerHistory(peerId, params, itemId);
 			return;
 		}
 	}
@@ -1561,6 +1564,18 @@ void MainWidget::showMessage(
 	}
 }
 
+void MainWidget::showForum(
+		not_null<Data::Forum*> forum,
+		const SectionShow &params) {
+	Expects(isPrimary() || (singlePeer() && singlePeer()->forum() == forum));
+
+	_dialogs->showForum(forum, params);
+
+	if (params.activation != anim::activation::background) {
+		_controller->hideLayer();
+	}
+}
+
 PeerData *MainWidget::peer() const {
 	return _history->peer();
 }
@@ -1749,7 +1764,7 @@ void MainWidget::showNewSection(
 	}
 
 	if (params.activation != anim::activation::background) {
-		controller()->window().hideSettingsAndLayer();
+		_controller->window().hideSettingsAndLayer();
 	}
 
 	_controller->setDialogsListFocused(false);
@@ -2657,7 +2672,7 @@ void MainWidget::handleHistoryBack() {
 		return;
 	}
 	const auto openedFolder = _controller->openedFolder().current();
-	const auto openedForum = _controller->openedForum().current();
+	const auto openedForum = _controller->shownForum().current();
 	const auto rootPeer = !_stack.empty()
 		? _stack.front()->peer()
 		: _history->peer()
diff --git a/Telegram/SourceFiles/mainwidget.h b/Telegram/SourceFiles/mainwidget.h
index c90f5002b..8e1abec74 100644
--- a/Telegram/SourceFiles/mainwidget.h
+++ b/Telegram/SourceFiles/mainwidget.h
@@ -45,6 +45,7 @@ namespace Data {
 class Thread;
 class WallPaper;
 struct ForwardDraft;
+class Forum;
 } // namespace Data
 
 namespace Dialogs {
@@ -216,13 +217,14 @@ public:
 
 	void toggleChooseChatTheme(not_null<PeerData*> peer);
 
-	void ui_showPeerHistory(
+	void showPeerHistory(
 		PeerId peer,
 		const SectionShow &params,
 		MsgId msgId);
 	void showMessage(
 		not_null<const HistoryItem*> item,
 		const SectionShow &params);
+	void showForum(not_null<Data::Forum*> forum, const SectionShow &params);
 
 	bool notify_switchInlineBotButtonReceived(const QString &query, UserData *samePeerBot, MsgId samePeerReplyTo);
 
diff --git a/Telegram/SourceFiles/ui/chat/group_call_bar.cpp b/Telegram/SourceFiles/ui/chat/group_call_bar.cpp
index 0ea7ad871..b915e4018 100644
--- a/Telegram/SourceFiles/ui/chat/group_call_bar.cpp
+++ b/Telegram/SourceFiles/ui/chat/group_call_bar.cpp
@@ -248,7 +248,7 @@ void GroupCallBar::setupRightButton(not_null<RoundButton*> button) {
 		const auto top = (st::historyReplyHeight
 			- st::lineWidth
 			- button->height()) / 2 + st::lineWidth;
-		const auto narrow = (outerWidth < st::columnMinimalWidthLeft);
+		const auto narrow = (outerWidth < st::columnMinimalWidthLeft / 2);
 		if (narrow) {
 			button->moveToLeft(
 				(outerWidth - buttonWidth) / 2,
@@ -265,7 +265,7 @@ void GroupCallBar::setupRightButton(not_null<RoundButton*> button) {
 void GroupCallBar::paint(Painter &p) {
 	p.fillRect(_inner->rect(), st::historyComposeAreaBg);
 
-	const auto narrow = (_inner->width() < st::columnMinimalWidthLeft);
+	const auto narrow = (_inner->width() < st::columnMinimalWidthLeft / 2);
 	if (!narrow) {
 		paintTitleAndStatus(p);
 		paintUserpics(p);
diff --git a/Telegram/SourceFiles/ui/chat/requests_bar.cpp b/Telegram/SourceFiles/ui/chat/requests_bar.cpp
index 69190a745..9636e02ce 100644
--- a/Telegram/SourceFiles/ui/chat/requests_bar.cpp
+++ b/Telegram/SourceFiles/ui/chat/requests_bar.cpp
@@ -151,7 +151,7 @@ void RequestsBar::paint(Painter &p) {
 	p.setPen(st::defaultMessageBar.titleFg);
 	p.setFont(font);
 
-	if (width >= st::columnMinimalWidthLeft) {
+	if (width >= st::columnMinimalWidthLeft / 2) {
 		const auto textLeft = userpicsLeft + _userpicsWidth + userpicsLeft;
 		const auto available = width - textLeft - userpicsLeft;
 		if (_textFull.isEmpty() || available < _textFull.maxWidth()) {
diff --git a/Telegram/SourceFiles/window/window_session_controller.cpp b/Telegram/SourceFiles/window/window_session_controller.cpp
index ee27fd125..78c2351b3 100644
--- a/Telegram/SourceFiles/window/window_session_controller.cpp
+++ b/Telegram/SourceFiles/window/window_session_controller.cpp
@@ -372,7 +372,7 @@ void SessionNavigation::showPeerByLinkResolved(
 	} else if (peer->isForum()) {
 		const auto itemId = info.messageId;
 		if (!itemId) {
-			parentController()->openForum(peer->asChannel(), params);
+			parentController()->showForum(peer->forum(), params);
 		} else if (const auto item = peer->owner().message(peer, itemId)) {
 			showMessageByLinkResolved(item, info);
 		} else {
@@ -974,13 +974,22 @@ void SessionController::closeFolder() {
 	_openedFolder = nullptr;
 }
 
-void SessionController::openForum(
-		not_null<ChannelData*> forum,
+void SessionController::showForum(
+		not_null<Data::Forum*> forum,
 		const SectionShow &params) {
-	Expects(forum->isForum());
-
-	_openedForumLifetime.destroy();
-	if (_openedForum.current() != forum) {
+	if (!isPrimary()) {
+		const auto primary = Core::App().primaryWindow();
+		if (&primary->account() != &session().account()) {
+			primary->showAccount(&session().account());
+		}
+		if (&primary->account() == &session().account()) {
+			primary->sessionController()->showForum(forum, params);
+		}
+		primary->activate();
+		return;
+	}
+	_shownForumLifetime.destroy();
+	if (_shownForum.current() != forum) {
 		resetFakeUnreadWhileOpened();
 	}
 	if (forum
@@ -988,24 +997,23 @@ void SessionController::openForum(
 		&& adaptive().isOneColumn()) {
 		clearSectionStack(params);
 	}
-	_openedForum = forum.get();
-	if (_openedForum.current() == forum) {
-		forum->forum()->destroyed(
-		) | rpl::start_with_next([=] {
-			closeForum();
-			showPeerHistory(
-				forum,
-				{ anim::type::normal, anim::activation::background });
-		}, _openedForumLifetime);
-	}
-	if (params.activation != anim::activation::background) {
-		hideLayer();
+	_shownForum = forum.get();
+	if (_shownForum.current() != forum) {
+		return;
 	}
+	forum->destroyed(
+	) | rpl::start_with_next([=, history = forum->history()] {
+		closeForum();
+		showPeerHistory(
+			history,
+			{ anim::type::normal, anim::activation::background });
+	}, _shownForumLifetime);
+	content()->showForum(forum, params);
 }
 
 void SessionController::closeForum() {
-	_openedForumLifetime.destroy();
-	_openedForum = nullptr;
+	_shownForumLifetime.destroy();
+	_shownForum = nullptr;
 }
 
 void SessionController::setupPremiumToast() {
@@ -1037,8 +1045,8 @@ const rpl::variable<Data::Folder*> &SessionController::openedFolder() const {
 	return _openedFolder;
 }
 
-const rpl::variable<ChannelData*> &SessionController::openedForum() const {
-	return _openedForum;
+const rpl::variable<Data::Forum*> &SessionController::shownForum() const {
+	return _shownForum;
 }
 
 void SessionController::setActiveChatEntry(Dialogs::RowDescriptor row) {
@@ -1062,9 +1070,9 @@ void SessionController::setActiveChatEntry(Dialogs::RowDescriptor row) {
 			) | rpl::start_with_next([=] {
 				clearSectionStack(
 					{ anim::type::normal, anim::activation::background });
-				openForum(channel,
+				showForum(channel->forum(),
 					{ anim::type::normal, anim::activation::background });
-			}, _openedForumLifetime);
+			}, _shownForumLifetime);
 		}
 	}
 	if (session().supportMode()) {
@@ -1674,7 +1682,7 @@ void SessionController::showPeerHistory(
 		PeerId peerId,
 		const SectionShow &params,
 		MsgId msgId) {
-	content()->ui_showPeerHistory(peerId, params, msgId);
+	content()->showPeerHistory(peerId, params, msgId);
 }
 
 void SessionController::showMessage(
diff --git a/Telegram/SourceFiles/window/window_session_controller.h b/Telegram/SourceFiles/window/window_session_controller.h
index 5c6bc6dda..05a54dfcc 100644
--- a/Telegram/SourceFiles/window/window_session_controller.h
+++ b/Telegram/SourceFiles/window/window_session_controller.h
@@ -69,6 +69,7 @@ namespace Data {
 struct CloudTheme;
 enum class CloudThemeType;
 class Thread;
+class Forum;
 class ForumTopic;
 } // namespace Data
 
@@ -151,19 +152,25 @@ struct SectionShow {
 	, activation(activation) {
 	}
 
-	SectionShow withWay(Way newWay) const {
+	[[nodiscard]] SectionShow withWay(Way newWay) const {
 		return SectionShow(newWay, animated, activation);
 	}
-	SectionShow withThirdColumn() const {
+	[[nodiscard]] SectionShow withThirdColumn() const {
 		auto copy = *this;
 		copy.thirdColumn = true;
 		return copy;
 	}
+	[[nodiscard]] SectionShow withChildColumn() const {
+		auto copy = *this;
+		copy.childColumn = true;
+		return copy;
+	}
 
 	Way way = Way::Forward;
 	anim::type animated = anim::type::normal;
 	anim::activation activation = anim::activation::normal;
 	bool thirdColumn = false;
+	bool childColumn = false;
 	Origin origin;
 
 };
@@ -358,11 +365,11 @@ public:
 	void closeFolder();
 	const rpl::variable<Data::Folder*> &openedFolder() const;
 
-	void openForum(
-		not_null<ChannelData*> forum,
+	void showForum(
+		not_null<Data::Forum*> forum,
 		const SectionShow &params = SectionShow::Way::ClearStack);
 	void closeForum();
-	const rpl::variable<ChannelData*> &openedForum() const;
+	const rpl::variable<Data::Forum*> &shownForum() const;
 
 	void setActiveChatEntry(Dialogs::RowDescriptor row);
 	void setActiveChatEntry(Dialogs::Key key);
@@ -634,8 +641,8 @@ private:
 
 	PeerData *_showEditPeer = nullptr;
 	rpl::variable<Data::Folder*> _openedFolder;
-	rpl::variable<ChannelData*> _openedForum;
-	rpl::lifetime _openedForumLifetime;
+	rpl::variable<Data::Forum*> _shownForum;
+	rpl::lifetime _shownForumLifetime;
 
 	rpl::event_stream<> _filtersMenuChanged;