Save last opened subsection within a launch.

Telegram/SourceFiles/data/data_channel.cpp

@@ -409,8 +409,8 @@ void ChannelData::setPendingRequestsCount(
 }
 
 bool ChannelData::useSubsectionTabs() const {
-	return isForum()
+	return amMonoforumAdmin()
-		&& (flags() & ChannelDataFlag::ForumTabs);
+		|| (isForum() && (flags() & ChannelDataFlag::ForumTabs));
 }
 
 ChatRestrictionsInfo ChannelData::KickedRestrictedRights(

Telegram/SourceFiles/data/data_forum.cpp

@@ -189,6 +189,9 @@ void Forum::applyTopicDeleted(MsgId rootId) {
 		reorderLastTopics();
 	}
 
+	if (_activeSubsectionTopic == raw) {
+		_activeSubsectionTopic = nullptr;
+	}
 	_topicDestroyed.fire(raw);
 	session().changes().topicUpdated(
 		raw,
@@ -259,6 +262,20 @@ const std::vector<not_null<ForumTopic*>> &Forum::recentTopics() const {
 	return _lastTopics;
 }
 
+void Forum::saveActiveSubsectionThread(not_null<Thread*> thread) {
+	if (const auto topic = thread->asTopic()) {
+		Assert(topic->forum() == this);
+		_activeSubsectionTopic = topic->creating() ? nullptr : topic;
+	} else {
+		Assert(thread == history());
+		_activeSubsectionTopic = nullptr;
+	}
+}
+
+Thread *Forum::activeSubsectionThread() const {
+	return _activeSubsectionTopic;
+}
+
 void Forum::listMessageChanged(HistoryItem *from, HistoryItem *to) {
 	if (from || to) {
 		reorderLastTopics();

Telegram/SourceFiles/data/data_forum.h

@@ -96,6 +96,9 @@ public:
 	[[nodiscard]] auto recentTopics() const
 		-> const std::vector<not_null<ForumTopic*>> &;
 
+	void saveActiveSubsectionThread(not_null<Thread*> thread);
+	[[nodiscard]] Thread *activeSubsectionThread() const;
+
 	[[nodiscard]] rpl::lifetime &lifetime() {
 		return _lifetime;
 	}
@@ -129,6 +132,8 @@ private:
 	std::vector<not_null<ForumTopic*>> _lastTopics;
 	int _lastTopicsVersion = 0;
 
+	ForumTopic *_activeSubsectionTopic = nullptr;
+
 	rpl::event_stream<> _chatsListChanges;
 	rpl::event_stream<> _chatsListLoadedEvents;
 

Telegram/SourceFiles/data/data_saved_messages.cpp

@@ -82,6 +82,20 @@ void SavedMessages::clear() {
 	_owningHistory = nullptr;
 }
 
+void SavedMessages::saveActiveSubsectionThread(not_null<Thread*> thread) {
+	if (const auto sublist = thread->asSublist()) {
+		Assert(sublist->parent() == this);
+		_activeSubsectionSublist = sublist;
+	} else {
+		Assert(thread == _owningHistory);
+		_activeSubsectionSublist = nullptr;
+	}
+}
+
+Thread *SavedMessages::activeSubsectionThread() const {
+	return _activeSubsectionSublist;
+}
+
 SavedMessages::~SavedMessages() {
 	clear();
 }

Telegram/SourceFiles/data/data_saved_messages.h

@@ -77,6 +77,9 @@ public:
 
 	void clear();
 
+	void saveActiveSubsectionThread(not_null<Thread*> thread);
+	Thread *activeSubsectionThread() const;
+
 	[[nodiscard]] rpl::lifetime &lifetime();
 
 private:
@@ -132,6 +135,8 @@ private:
 	rpl::event_stream<> _chatsListChanges;
 	rpl::event_stream<> _chatsListLoadedEvents;
 
+	SavedSublist *_activeSubsectionSublist = nullptr;
+
 	bool _pinnedLoaded = false;
 	bool _unsupported = false;
 

Telegram/SourceFiles/data/data_thread.cpp

@@ -7,9 +7,12 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 */
 #include "data/data_thread.h"
 
+#include "data/data_forum.h"
 #include "data/data_forum_topic.h"
 #include "data/data_changes.h"
+#include "data/data_channel.h"
 #include "data/data_peer.h"
+#include "data/data_saved_messages.h"
 #include "data/data_saved_sublist.h"
 #include "history/history.h"
 #include "history/history_item.h"
@@ -202,4 +205,16 @@ void Thread::setHasPinnedMessages(bool has) {
 		EntryUpdate::Flag::HasPinnedMessages);
 }
 
+void Thread::saveMeAsActiveSubsectionThread() {
+	if (const auto channel = owningHistory()->peer->asChannel()) {
+		if (channel->useSubsectionTabs()) {
+			if (const auto forum = channel->forum()) {
+				forum->saveActiveSubsectionThread(this);
+			} else if (const auto monoforum = channel->monoforum()) {
+				monoforum->saveActiveSubsectionThread(this);
+			}
+		}
+	}
+}
+
 } // namespace Data

Telegram/SourceFiles/data/data_thread.h

@@ -120,6 +120,8 @@ public:
 	[[nodiscard]] bool hasPinnedMessages() const;
 	void setHasPinnedMessages(bool has);
 
+	void saveMeAsActiveSubsectionThread();
+
 protected:
 	void setUnreadMarkFlag(bool unread);
 

Telegram/SourceFiles/dialogs/dialogs_widget.cpp

@@ -79,6 +79,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "data/data_changes.h"
 #include "data/data_download_manager.h"
 #include "data/data_chat_filters.h"
+#include "data/data_saved_messages.h"
 #include "data/data_saved_sublist.h"
 #include "data/data_stories.h"
 #include "info/downloads/info_downloads_widget.h"
@@ -920,7 +921,8 @@ void Widget::chosenRow(const ChosenRow &row) {
 		&& history->isForum()
 		&& !row.message.fullId
 		&& (!controller()->adaptive().isOneColumn()
-			|| !history->peer->forum()->channel()->viewForumAsMessages())) {
+			|| !history->peer->forum()->channel()->viewForumAsMessages()
+			|| history->peer->forum()->channel()->useSubsectionTabs())) {
 		const auto forum = history->peer->forum();
 		if (controller()->shownForum().current() == forum) {
 			controller()->closeForum();
@@ -943,6 +945,26 @@ void Widget::chosenRow(const ChosenRow &row) {
 			}
 		}
 		return;
+	} else if (history
+		&& history->amMonoforumAdmin()
+		&& !row.message.fullId) {
+		const auto monoforum = history->peer->monoforum();
+		if (row.newWindow) {
+			controller()->showInNewWindow(
+				Window::SeparateId(Window::SeparateType::Chat, history));
+		} else {
+			if (const auto active = monoforum->activeSubsectionThread()) {
+				controller()->showThread(
+					active,
+					ShowAtUnreadMsgId,
+					Window::SectionShow::Way::ClearStack);
+			} else {
+				controller()->showPeerHistory(
+					history,
+					Window::SectionShow::Way::ClearStack);
+			}
+		}
+		return;
 	} else if (history) {
 		const auto peer = history->peer;
 		const auto showAtMsgId = controller()->uniqueChatsInSearchResults()

Telegram/SourceFiles/history/history_widget.cpp

@@ -4834,6 +4834,10 @@ void HistoryWidget::doneShow() {
 	controller()->widget()->setInnerFocus();
 	_preserveScrollTop = false;
 	checkSuggestToGigagroup();
+
+	if (_history) {
+		_history->saveMeAsActiveSubsectionThread();
+	}
 }
 
 void HistoryWidget::cornerButtonsShowAtPosition(

Telegram/SourceFiles/history/view/history_view_chat_section.cpp

@@ -2880,6 +2880,12 @@ void ChatWidget::showFinishedHook() {
 	// because after that the method showChildren() is called.
 	setupDragArea();
 	updatePinnedVisibility();
+
+	if (_topic) {
+		_topic->saveMeAsActiveSubsectionThread();
+	} else if (_sublist) {
+		_sublist->saveMeAsActiveSubsectionThread();
+	}
 }
 
 bool ChatWidget::floatPlayerHandleWheelEvent(QEvent *e) {

Telegram/SourceFiles/window/window_session_controller.cpp

@@ -586,7 +586,8 @@ void SessionNavigation::showPeerByLinkResolved(
 		if (const auto forum = peer->forum()) {
 			if (controller->windowId().hasChatsList()
 				&& !controller->adaptive().isOneColumn()
-				&& controller->shownForum().current() != forum) {
+				&& controller->shownForum().current() != forum
+				&& !forum->channel()->useSubsectionTabs()) {
 				controller->showForum(forum);
 			}
 		}
@@ -1878,7 +1879,11 @@ void SessionController::showForum(
 	if (showForumInDifferentWindow(forum, params)) {
 		return;
 	} else if (forum->channel()->useSubsectionTabs()) {
-		showPeerHistory(forum->channel(), params);
+		if (const auto active = forum->activeSubsectionThread()) {
+			showThread(active, ShowAtUnreadMsgId, params);
+		} else {
+			showPeerHistory(forum->channel(), params);
+		}
 		return;
 	}
 	_shownForumLifetime.destroy();
@@ -1992,9 +1997,9 @@ void SessionController::setActiveChatEntry(Dialogs::RowDescriptor row) {
 			Data::PeerFlagValue(
 				channel,
 				ChannelData::Flag::Forum
-			) | rpl::filter(
+			) | rpl::filter([=](bool forum) {
-				rpl::mappers::_1
+				return forum && !channel->useSubsectionTabs();
-			) | rpl::start_with_next([=] {
+			}) | rpl::start_with_next([=] {
 				clearSectionStack(
 					{ anim::type::normal, anim::activation::background });
 				showForum(channel->forum(),