Add "Show Topics List" button to topic profile.

Telegram/Resources/langs/lang.strings

@@ -3559,6 +3559,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 "lng_forum_no_messages" = "No messages";
 "lng_forum_messages#one" = "{count} message";
 "lng_forum_messages#other" = "{count} messages";
+"lng_forum_show_topics_list" = "Show Topics List";
 
 // Wnd specific
 

Telegram/SourceFiles/info/profile/info_profile_actions.cpp

@@ -194,6 +194,7 @@ private:
 	object_ptr<Ui::RpWidget> setupInfo();
 	object_ptr<Ui::RpWidget> setupMuteToggle();
 	void setupMainButtons();
+	Ui::MultiSlideTracker fillTopicButtons();
 	Ui::MultiSlideTracker fillUserButtons(
 		not_null<UserData*> user);
 	Ui::MultiSlideTracker fillChannelButtons(
@@ -538,11 +539,15 @@ void DetailsFiller::setupMainButtons() {
 		auto tracker = callback();
 		topSkip->toggleOn(std::move(tracker).atLeastOneShownValue());
 	};
-	if (auto user = _peer->asUser()) {
+	if (_topic) {
+		wrapButtons([=] {
+			return fillTopicButtons();
+		});
+	} else if (const auto user = _peer->asUser()) {
 		wrapButtons([=] {
 			return fillUserButtons(user);
 		});
-	} else if (auto channel = _peer->asChannel()) {
+	} else if (const auto channel = _peer->asChannel()) {
 		if (!channel->isMegagroup()) {
 			wrapButtons([=] {
 				return fillChannelButtons(channel);
@@ -551,6 +556,26 @@ void DetailsFiller::setupMainButtons() {
 	}
 }
 
+Ui::MultiSlideTracker DetailsFiller::fillTopicButtons() {
+	using namespace rpl::mappers;
+
+	Ui::MultiSlideTracker tracker;
+	const auto window = _controller->parentController();
+
+	const auto channel = _topic->channel().get();
+	auto showTopicsVisible = rpl::combine(
+		window->adaptive().oneColumnValue(),
+		window->openedForum().value(),
+		_1 || (_2 != channel));
+	AddMainButton(
+		_wrap,
+		tr::lng_forum_show_topics_list(),
+		std::move(showTopicsVisible),
+		[=] { window->openForum(channel); },
+		tracker);
+	return tracker;
+}
+
 Ui::MultiSlideTracker DetailsFiller::fillUserButtons(
 		not_null<UserData*> user) {
 	using namespace rpl::mappers;

Telegram/SourceFiles/window/window_session_controller.cpp

@@ -983,7 +983,9 @@ void SessionController::openForum(
 	if (_openedForum.current() != forum) {
 		resetFakeUnreadWhileOpened();
 	}
-	if (forum && _activeChatEntry.current().key.peer()) {
+	if (forum
+		&& _activeChatEntry.current().key.peer()
+		&& adaptive().isOneColumn()) {
 		clearSectionStack(params);
 	}
 	_openedForum = forum.get();
@@ -996,6 +998,9 @@ void SessionController::openForum(
 				{ anim::type::normal, anim::activation::background });
 		}, _openedForumLifetime);
 	}
+	if (params.activation != anim::activation::background) {
+		hideLayer();
+	}
 }
 
 void SessionController::closeForum() {