new file mode 100644
--- /dev/null
+++ b/src/testdir/samples/box.txt
@@ -0,0 +1,601 @@
+void BackgroundBox::prepare() {
+	setTitle(tr::lng_backgrounds_header());
+
+	addButton(tr::lng_close(), [=] { closeBox(); });
+
+	setDimensions(st::boxWideWidth, st::boxMaxListHeight);
+
+	auto wrap = object_ptr<Ui::VerticalLayout>(this);
+	const auto container = wrap.data();
+
+	Settings::AddSkip(container);
+
+	const auto button = container->add(Settings::CreateButton(
+		container,
+		tr::lng_settings_bg_from_file(),
+		st::infoProfileButton));
+	object_ptr<Info::Profile::FloatingIcon>(
+		button,
+		st::infoIconMediaPhoto,
+		st::infoSharedMediaButtonIconPosition);
+
+	button->setClickedCallback([=] {
+		chooseFromFile();
+	});
+
+	Settings::AddSkip(container);
+	Settings::AddDivider(container);
+
+	_inner = container->add(
+		object_ptr<Inner>(this, &_controller->session(), _forPeer));
+
+	container->resizeToWidth(st::boxWideWidth);
+
+	setInnerWidget(std::move(wrap), st::backgroundScroll);
+	setInnerTopSkip(st::lineWidth);
+
+	_inner->chooseEvents(
+	) | rpl::start_with_next([=](const Data::WallPaper &paper) {
+		chosen(paper);
+	}, _inner->lifetime());
+
+	_inner->removeRequests(
+	) | rpl::start_with_next([=](const Data::WallPaper &paper) {
+		removePaper(paper);
+	}, _inner->lifetime());
+}
+
+void BackgroundBox::chooseFromFile() {
+	const auto filterStart = _forPeer
+		? u"Image files (*"_q
+		: u"Theme files (*.tdesktop-theme *.tdesktop-palette *"_q;
+	auto filters = QStringList(
+		filterStart
+		+ Ui::ImageExtensions().join(u" *"_q)
+		+ u")"_q);
+	filters.push_back(FileDialog::AllFilesFilter());
+	const auto callback = [=](const FileDialog::OpenResult &result) {
+		if (result.paths.isEmpty() && result.remoteContent.isEmpty()) {
+			return;
+		}
+
+		if (!_forPeer && !result.paths.isEmpty()) {
+			const auto filePath = result.paths.front();
+			const auto hasExtension = [&](QLatin1String extension) {
+				return filePath.endsWith(extension, Qt::CaseInsensitive);
+			};
+			if (hasExtension(qstr(".tdesktop-theme"))
+				|| hasExtension(qstr(".tdesktop-palette"))) {
+				Window::Theme::Apply(filePath);
+				return;
+			}
+		}
+
+		auto image = Images::Read({
+			.path = result.paths.isEmpty() ? QString() : result.paths.front(),
+			.content = result.remoteContent,
+			.forceOpaque = true,
+		}).image;
+		if (image.isNull() || image.width() <= 0 || image.height() <= 0) {
+			return;
+		}
+		auto local = Data::CustomWallPaper();
+		local.setLocalImageAsThumbnail(std::make_shared<Image>(
+			std::move(image)));
+		_controller->show(Box<BackgroundPreviewBox>(
+			_controller,
+			local,
+			BackgroundPreviewArgs{ _forPeer }));
+	};
+	FileDialog::GetOpenPath(
+		this,
+		tr::lng_choose_image(tr::now),
+		filters.join(u";;"_q),
+		crl::guard(this, callback));
+}
+
+bool BackgroundBox::hasDefaultForPeer() const {
+	Expects(_forPeer != nullptr);
+
+	const auto paper = _forPeer->wallPaper();
+	if (!paper) {
+		return true;
+	}
+	const auto reset = _inner->resolveResetCustomPaper();
+	Assert(reset.has_value());
+	return (paper->id() == reset->id());
+}
+
+bool BackgroundBox::chosenDefaultForPeer(
+		const Data::WallPaper &paper) const {
+	if (!_forPeer) {
+		return false;
+	}
+
+	const auto reset = _inner->resolveResetCustomPaper();
+	Assert(reset.has_value());
+	return (paper.id() == reset->id());
+}
+
+void BackgroundBox::chosen(const Data::WallPaper &paper) {
+	if (chosenDefaultForPeer(paper)) {
+		if (!hasDefaultForPeer()) {
+			const auto reset = crl::guard(this, [=](Fn<void()> close) {
+				resetForPeer();
+				close();
+			});
+			_controller->show(Ui::MakeConfirmBox({
+				.text = tr::lng_background_sure_reset_default(),
+				.confirmed = reset,
+				.confirmText = tr::lng_background_reset_default(),
+			}));
+		} else {
+			closeBox();
+		}
+		return;
+	}
+	_controller->show(Box<BackgroundPreviewBox>(
+		_controller,
+		paper,
+		BackgroundPreviewArgs{ _forPeer }));
+}
+
+void BackgroundBox::resetForPeer() {
+	const auto api = &_controller->session().api();
+	api->request(MTPmessages_SetChatWallPaper(
+		MTP_flags(0),
+		_forPeer->input,
+		MTPInputWallPaper(),
+		MTPWallPaperSettings(),
+		MTPint()
+	)).done([=](const MTPUpdates &result) {
+		api->applyUpdates(result);
+	}).send();
+
+	const auto weak = Ui::MakeWeak(this);
+	_forPeer->setWallPaper(std::nullopt);
+	if (weak) {
+		_controller->finishChatThemeEdit(_forPeer);
+	}
+}
+
+void BackgroundBox::removePaper(const Data::WallPaper &paper) {
+	const auto session = &_controller->session();
+	const auto remove = [=, weak = Ui::MakeWeak(this)](Fn<void()> &&close) {
+		close();
+		if (weak) {
+			weak->_inner->removePaper(paper);
+		}
+		session->data().removeWallpaper(paper);
+		session->api().request(MTPaccount_SaveWallPaper(
+			paper.mtpInput(session),
+			MTP_bool(true),
+			paper.mtpSettings()
+		)).send();
+	};
+	_controller->show(Ui::MakeConfirmBox({
+		.text = tr::lng_background_sure_delete(),
+		.confirmed = remove,
+		.confirmText = tr::lng_selected_delete(),
+	}));
+}
+
+BackgroundBox::Inner::Inner(
+	QWidget *parent,
+	not_null<Main::Session*> session,
+	PeerData *forPeer)
+: RpWidget(parent)
+, _session(session)
+, _forPeer(forPeer)
+, _api(&_session->mtp())
+, _check(std::make_unique<Ui::RoundCheckbox>(st::overviewCheck, [=] { update(); })) {
+	_check->setChecked(true, anim::type::instant);
+	resize(st::boxWideWidth, 2 * (st::backgroundSize.height() + st::backgroundPadding) + st::backgroundPadding);
+	Window::Theme::IsNightModeValue(
+	) | rpl::start_with_next([=] {
+		updatePapers();
+	}, lifetime());
+	requestPapers();
+
+	_session->downloaderTaskFinished(
+	) | rpl::start_with_next([=] {
+		update();
+	}, lifetime());
+
+	style::PaletteChanged(
+	) | rpl::start_with_next([=] {
+		_check->invalidateCache();
+	}, lifetime());
+
+	using Update = Window::Theme::BackgroundUpdate;
+	Window::Theme::Background()->updates(
+	) | rpl::start_with_next([=](const Update &update) {
+		if (update.type == Update::Type::New) {
+			sortPapers();
+			requestPapers();
+			this->update();
+		}
+	}, lifetime());
+
+
+	setMouseTracking(true);
+}
+
+void BackgroundBox::Inner::requestPapers() {
+	_api.request(MTPaccount_GetWallPapers(
+		MTP_long(_session->data().wallpapersHash())
+	)).done([=](const MTPaccount_WallPapers &result) {
+		if (_session->data().updateWallpapers(result)) {
+			updatePapers();
+		}
+	}).send();
+}
+
+auto BackgroundBox::Inner::resolveResetCustomPaper() const
+-> std::optional<Data::WallPaper> {
+	if (!_forPeer) {
+		return {};
+	}
+	const auto nonCustom = Window::Theme::Background()->paper();
+	const auto themeEmoji = _forPeer->themeEmoji();
+	if (themeEmoji.isEmpty()) {
+		return nonCustom;
+	}
+	const auto &themes = _forPeer->owner().cloudThemes();
+	const auto theme = themes.themeForEmoji(themeEmoji);
+	if (!theme) {
+		return nonCustom;
+	}
+	using Type = Data::CloudTheme::Type;  XXXXX
+	const auto dark = Window::Theme::IsNightMode();
+	const auto i = theme->settings.find(dark ? Type::Dark : Type::Light);
+	if (i != end(theme->settings) && i->second.paper) {
+		return *i->second.paper;
+	}
+	return nonCustom;
+}
+
+void BackgroundBox::Inner::pushCustomPapers() {
+	auto customId = uint64();
+	if (const auto custom = _forPeer ? _forPeer->wallPaper() : nullptr) {
+		customId = custom->id();
+		const auto j = ranges::find(
+			_papers,
+			custom->id(),
+			[](const Paper &paper) { return paper.data.id(); });
+		if (j != end(_papers)) {
+			j->data = j->data.withParamsFrom(*custom);
+		} else {
+			_papers.insert(begin(_papers), Paper{ *custom });
+		}
+	}
+	if (const auto reset = resolveResetCustomPaper()) {
+		_insertedResetId = reset->id();
+		const auto j = ranges::find(
+			_papers,
+			_insertedResetId,
+			[](const Paper &paper) { return paper.data.id(); });
+		if (j != end(_papers)) {
+			if (_insertedResetId != customId) {
+				j->data = j->data.withParamsFrom(*reset);
+			}
+		} else {
+			_papers.insert(begin(_papers), Paper{ *reset });
+		}
+	}
+}
+
+void BackgroundBox::Inner::sortPapers() {
+	const auto currentCustom = _forPeer ? _forPeer->wallPaper() : nullptr;
+	_currentId = currentCustom
+		? currentCustom->id()
+		: _insertedResetId
+		? _insertedResetId
+		: Window::Theme::Background()->id();
+	const auto dark = Window::Theme::IsNightMode();
+	ranges::stable_sort(_papers, std::greater<>(), [&](const Paper &paper) {
+		const auto &data = paper.data;
+		return std::make_tuple(
+			_insertedResetId && (_insertedResetId == data.id()),
+			data.id() == _currentId,
+			dark ? data.isDark() : !data.isDark(),
+			Data::IsDefaultWallPaper(data),
+			!data.isDefault() && !Data::IsLegacy1DefaultWallPaper(data),
+			Data::IsLegacy3DefaultWallPaper(data),
+			Data::IsLegacy2DefaultWallPaper(data),
+			Data::IsLegacy1DefaultWallPaper(data));
+	});
+	if (!_papers.empty()
+		&& _papers.front().data.id() == _currentId
+		&& !currentCustom
+		&& !_insertedResetId) {
+		_papers.front().data = _papers.front().data.withParamsFrom(
+			Window::Theme::Background()->paper());
+	}
+}
+
+void BackgroundBox::Inner::updatePapers() {
+	if (_session->data().wallpapers().empty()) {
+		return;
+	}
+	_over = _overDown = Selection();
+
+	_papers = _session->data().wallpapers(
+	) | ranges::views::filter([&](const Data::WallPaper &paper) {
+		return (!paper.isPattern() || !paper.backgroundColors().empty())
+			&& (!_forPeer
+				|| (!Data::IsDefaultWallPaper(paper)
+					&& (Data::IsCloudWallPaper(paper)
+						|| Data::IsCustomWallPaper(paper))));
+	}) | ranges::views::transform([](const Data::WallPaper &paper) {
+		return Paper{ paper };
+	}) | ranges::to_vector;
+	pushCustomPapers();
+	sortPapers();
+	resizeToContentAndPreload();
+}
+
+void BackgroundBox::Inner::resizeToContentAndPreload() {
+	const auto count = _papers.size();
+	const auto rows = (count / kBackgroundsInRow)
+		+ (count % kBackgroundsInRow ? 1 : 0);
+
+	resize(
+		st::boxWideWidth,
+		(rows * (st::backgroundSize.height() + st::backgroundPadding)
+			+ st::backgroundPadding));
+
+	const auto preload = kBackgroundsInRow * 3;
+	for (const auto &paper : _papers | ranges::views::take(preload)) {
+		if (!paper.data.localThumbnail() && !paper.dataMedia) {
+			if (const auto document = paper.data.document()) {
+				paper.dataMedia = document->createMediaView();
+				paper.dataMedia->thumbnailWanted(paper.data.fileOrigin());
+			}
+		}
+	}
+	update();
+}
+
+void BackgroundBox::Inner::paintEvent(QPaintEvent *e) {
+	QRect r(e->rect());
+	auto p = QPainter(this);
+
+	if (_papers.empty()) {
+		p.setFont(st::noContactsFont);
+		p.setPen(st::noContactsColor);
+		p.drawText(QRect(0, 0, width(), st::noContactsHeight), tr::lng_contacts_loading(tr::now), style::al_center);
+		return;
+	}
+	auto row = 0;
+	auto column = 0;
+	for (const auto &paper : _papers) {
+		const auto increment = gsl::finally([&] {
+			++column;
+			if (column == kBackgroundsInRow) {
+				column = 0;
+				++row;
+			}
+		});
+		if ((st::backgroundSize.height() + st::backgroundPadding) * (row + 1) <= r.top()) {
+			continue;
+		} else if ((st::backgroundSize.height() + st::backgroundPadding) * row >= r.top() + r.height()) {
+			break;
+		}
+		paintPaper(p, paper, column, row);
+	}
+}
+
+void BackgroundBox::Inner::validatePaperThumbnail(
+		const Paper &paper) const {
+	if (!paper.thumbnail.isNull()) {
+		return;
+	}
+	const auto localThumbnail = paper.data.localThumbnail();
+	if (!localThumbnail) {
+		if (const auto document = paper.data.document()) {
+			if (!paper.dataMedia) {
+				paper.dataMedia = document->createMediaView();
+				paper.dataMedia->thumbnailWanted(paper.data.fileOrigin());
+			}
+			if (!paper.dataMedia->thumbnail()) {
+				return;
+			}
+		} else if (!paper.data.backgroundColors().empty()) {
+			paper.thumbnail = Ui::PixmapFromImage(
+				Ui::GenerateBackgroundImage(
+					st::backgroundSize * cIntRetinaFactor(),
+					paper.data.backgroundColors(),
+					paper.data.gradientRotation()));
+			paper.thumbnail.setDevicePixelRatio(cRetinaFactor());
+			return;
+		} else {
+			return;
+		}
+	}
+	const auto thumbnail = localThumbnail
+		? localThumbnail
+		: paper.dataMedia->thumbnail();
+	auto original = thumbnail->original();
+	if (paper.data.isPattern()) {
+		original = Ui::PreparePatternImage(
+			std::move(original),
+			paper.data.backgroundColors(),
+			paper.data.gradientRotation(),
+			paper.data.patternOpacity());
+	}
+	paper.thumbnail = Ui::PixmapFromImage(TakeMiddleSample(
+		original,
+		st::backgroundSize));
+	paper.thumbnail.setDevicePixelRatio(cRetinaFactor());
+}
+
+void BackgroundBox::Inner::paintPaper(
+		QPainter &p,
+		const Paper &paper,
+		int column,
+		int row) const {
+	const auto x = st::backgroundPadding + column * (st::backgroundSize.width() + st::backgroundPadding);
+	const auto y = st::backgroundPadding + row * (st::backgroundSize.height() + st::backgroundPadding);
+	validatePaperThumbnail(paper);
+	if (!paper.thumbnail.isNull()) {
+		p.drawPixmap(x, y, paper.thumbnail);
+	}
+
+	const auto over = !v::is_null(_overDown) ? _overDown : _over;
+	if (paper.data.id() == _currentId) {
+		const auto checkLeft = x + st::backgroundSize.width() - st::overviewCheckSkip - st::overviewCheck.size;
+		const auto checkTop = y + st::backgroundSize.height() - st::overviewCheckSkip - st::overviewCheck.size;
+		_check->paint(p, checkLeft, checkTop, width());
+	} else if (Data::IsCloudWallPaper(paper.data)
+		&& !Data::IsDefaultWallPaper(paper.data)
+		&& !Data::IsLegacy2DefaultWallPaper(paper.data)
+		&& !Data::IsLegacy3DefaultWallPaper(paper.data)
+		&& !v::is_null(over)
+		&& (&paper == &_papers[getSelectionIndex(over)])) {
+		const auto deleteSelected = v::is<DeleteSelected>(over);
+		const auto deletePos = QPoint(x + st::backgroundSize.width() - st::stickerPanDeleteIconBg.width(), y);
+		p.setOpacity(deleteSelected ? st::stickerPanDeleteOpacityBgOver : st::stickerPanDeleteOpacityBg);
+		st::stickerPanDeleteIconBg.paint(p, deletePos, width());
+		p.setOpacity(deleteSelected ? st::stickerPanDeleteOpacityFgOver : st::stickerPanDeleteOpacityFg);
+		st::stickerPanDeleteIconFg.paint(p, deletePos, width());
+		p.setOpacity(1.);
+	}
+}
+
+void BackgroundBox::Inner::mouseMoveEvent(QMouseEvent *e) {
+	const auto newOver = [&] {
+		const auto x = e->pos().x();
+		const auto y = e->pos().y();
+		const auto width = st::backgroundSize.width();
+		const auto height = st::backgroundSize.height();
+		const auto skip = st::backgroundPadding;
+		const auto row = int((y - skip) / (height + skip));
+		const auto column = int((x - skip) / (width + skip));
+		const auto result = row * kBackgroundsInRow + column;
+		if (y - row * (height + skip) > skip + height) {
+			return Selection();
+		} else if (x - column * (width + skip) > skip + width) {
+			return Selection();
+		} else if (result >= _papers.size()) {
+			return Selection();
+		}
+		auto &data = _papers[result].data;
+		const auto deleteLeft = (column + 1) * (width + skip)
+			- st::stickerPanDeleteIconBg.width();
+		const auto deleteBottom = row * (height + skip) + skip
+			+ st::stickerPanDeleteIconBg.height();
+		const auto inDelete = (x >= deleteLeft)
+			&& (y < deleteBottom)
+			&& Data::IsCloudWallPaper(data)
+			&& !Data::IsDefaultWallPaper(data)
+			&& !Data::IsLegacy2DefaultWallPaper(data)
+			&& !Data::IsLegacy3DefaultWallPaper(data)
+			&& (_currentId != data.id());
+		return (result >= _papers.size())
+			? Selection()
+			: inDelete
+			? Selection(DeleteSelected{ result })
+			: Selection(Selected{ result });
+	}();
+	if (_over != newOver) {
+		repaintPaper(getSelectionIndex(_over));
+		_over = newOver;
+		repaintPaper(getSelectionIndex(_over));
+		setCursor((!v::is_null(_over) || !v::is_null(_overDown))
+			? style::cur_pointer
+			: style::cur_default);
+	}
+}
+
+void BackgroundBox::Inner::repaintPaper(int index) {
+	if (index < 0 || index >= _papers.size()) {
+		return;
+	}
+	const auto row = (index / kBackgroundsInRow);
+	const auto column = (index % kBackgroundsInRow);
+	const auto width = st::backgroundSize.width();
+	const auto height = st::backgroundSize.height();
+	const auto skip = st::backgroundPadding;
+	update(
+		(width + skip) * column + skip,
+		(height + skip) * row + skip,
+		width,
+		height);
+}
+
+void BackgroundBox::Inner::mousePressEvent(QMouseEvent *e) {
+	_overDown = _over;
+}
+
+int BackgroundBox::Inner::getSelectionIndex(
+		const Selection &selection) const {
+	return v::match(selection, [](const Selected &data) {
+		return data.index;
+	}, [](const DeleteSelected &data) {
+		return data.index;
+	}, [](v::null_t) {
+		return -1;
+	});
+}
+
+void BackgroundBox::Inner::mouseReleaseEvent(QMouseEvent *e) {
+	if (base::take(_overDown) == _over && !v::is_null(_over)) {
+		const auto index = getSelectionIndex(_over);
+		if (index >= 0 && index < _papers.size()) {
+			if (std::get_if<DeleteSelected>(&_over)) {
+				_backgroundRemove.fire_copy(_papers[index].data);
+			} else if (std::get_if<Selected>(&_over)) {
+				auto &paper = _papers[index];
+				if (!paper.dataMedia) {
+					if (const auto document = paper.data.document()) {
+						// Keep it alive while it is on the screen.
+						paper.dataMedia = document->createMediaView();
+					}
+				}
+				_backgroundChosen.fire_copy(paper.data);
+			}
+		}
+	} else if (v::is_null(_over)) {
+		setCursor(style::cur_default);
+	}
+}
+
+void BackgroundBox::Inner::visibleTopBottomUpdated(
+		int visibleTop,
+		int visibleBottom) {
+	for (auto i = 0, count = int(_papers.size()); i != count; ++i) {
+		const auto row = (i / kBackgroundsInRow);
+		const auto height = st::backgroundSize.height();
+		const auto skip = st::backgroundPadding;
+		const auto top = skip + row * (height + skip);
+		const auto bottom = top + height;
+		if ((bottom <= visibleTop || top >= visibleBottom)
+			&& !_papers[i].thumbnail.isNull()) {
+			_papers[i].dataMedia = nullptr;
+		}
+	}
+}
+
+rpl::producer<Data::WallPaper> BackgroundBox::Inner::chooseEvents() const {
+	return _backgroundChosen.events();
+}
+
+auto BackgroundBox::Inner::removeRequests() const
+-> rpl::producer<Data::WallPaper> {
+	return _backgroundRemove.events();
+}
+
+void BackgroundBox::Inner::removePaper(const Data::WallPaper &data) {
+	const auto i = ranges::find(
+		_papers,
+		data.id(),
+		[](const Paper &paper) { return paper.data.id(); });
+	if (i != end(_papers)) {
+		_papers.erase(i);
+		_over = _overDown = Selection();
+		resizeToContentAndPreload();
+	}
+}
+
+BackgroundBox::Inner::~Inner() = default;