diff --git a/Telegram/SourceFiles/auth_session.cpp b/Telegram/SourceFiles/auth_session.cpp
index 9c3295adc..6b9e20791 100644
--- a/Telegram/SourceFiles/auth_session.cpp
+++ b/Telegram/SourceFiles/auth_session.cpp
@@ -73,7 +73,11 @@ QByteArray AuthSessionData::serialize() const {
 		}
 		stream << qint32(_variables.thirdSectionInfoEnabled ? 1 : 0);
 		stream << qint32(_variables.smallDialogsList ? 1 : 0);
-		stream << qint32(snap(qRound(_variables.dialogsWidthRatio.current() * 1000000), 0, 1000000));
+		stream << qint32(snap(
+			qRound(_variables.dialogsWidthRatio.current() * 1000000),
+			0,
+			1000000));
+		stream << qint32(_variables.thirdColumnWidth.current());
 	}
 	return result;
 }
@@ -96,6 +100,7 @@ void AuthSessionData::constructFromSerialized(const QByteArray &serialized) {
 	qint32 thirdSectionInfoEnabled = 0;
 	qint32 smallDialogsList = 0;
 	float64 dialogsWidthRatio = _variables.dialogsWidthRatio.current();
+	int thirdColumnWidth = _variables.thirdColumnWidth.current();
 	stream >> selectorTab;
 	stream >> lastSeenWarningSeen;
 	if (!stream.atEnd()) {
@@ -137,6 +142,9 @@ void AuthSessionData::constructFromSerialized(const QByteArray &serialized) {
 		qint32 value = 0;
 		stream >> value;
 		dialogsWidthRatio = snap(value / 1000000., 0., 1.);
+
+		stream >> value;
+		thirdColumnWidth = value;
 	}
 	if (stream.status() != QDataStream::Ok) {
 		LOG(("App Error: Bad data for AuthSessionData::constructFromSerialized()"));
@@ -170,6 +178,7 @@ void AuthSessionData::constructFromSerialized(const QByteArray &serialized) {
 	_variables.thirdSectionInfoEnabled = thirdSectionInfoEnabled;
 	_variables.smallDialogsList = smallDialogsList;
 	_variables.dialogsWidthRatio = dialogsWidthRatio;
+	_variables.thirdColumnWidth = thirdColumnWidth;
 	if (_variables.thirdSectionInfoEnabled) {
 		_variables.tabbedSelectorSectionEnabled = false;
 	}
diff --git a/Telegram/SourceFiles/auth_session.h b/Telegram/SourceFiles/auth_session.h
index 5f3ec219b..0074ce2e5 100644
--- a/Telegram/SourceFiles/auth_session.h
+++ b/Telegram/SourceFiles/auth_session.h
@@ -224,6 +224,15 @@ public:
 	rpl::producer<float64> dialogsWidthRatioChanges() const {
 		return _variables.dialogsWidthRatio.changes();
 	}
+	void setThirdColumnWidth(int width) {
+		_variables.thirdColumnWidth = width;
+	}
+	int thirdColumnWidth() const {
+		return _variables.thirdColumnWidth.current();
+	}
+	rpl::producer<int> thirdColumnWidthChanges() const {
+		return _variables.thirdColumnWidth.changes();
+	}
 
 	void markStickersUpdated() {
 		_stickersUpdated.fire({});
@@ -321,6 +330,7 @@ private:
 		Variables();
 
 		static constexpr auto kDefaultDialogsWidthRatio = 5. / 14;
+		static constexpr auto kDefaultThirdColumnWidth = 0;
 
 		bool lastSeenWarningSeen = false;
 		ChatHelpers::SelectorTab selectorTab; // per-window
@@ -332,7 +342,10 @@ private:
 		base::flat_set<PeerId> groupStickersSectionHidden;
 		bool thirdSectionInfoEnabled = true; // per-window
 		bool smallDialogsList = false; // per-window
-		rpl::variable<float64> dialogsWidthRatio = kDefaultDialogsWidthRatio; // per-window
+		rpl::variable<float64> dialogsWidthRatio
+			= kDefaultDialogsWidthRatio; // per-window
+		rpl::variable<int> thirdColumnWidth
+			= kDefaultThirdColumnWidth; // per-window
 	};
 
 	bool stickersUpdateNeeded(TimeMs lastUpdate, TimeMs now) const {
diff --git a/Telegram/SourceFiles/dialogs/dialogs.style b/Telegram/SourceFiles/dialogs/dialogs.style
index 32e6f7758..0b042e4c5 100644
--- a/Telegram/SourceFiles/dialogs/dialogs.style
+++ b/Telegram/SourceFiles/dialogs/dialogs.style
@@ -51,8 +51,6 @@ dialogsImportantBarHeight: 37px;
 
 dialogsSkip: 8px;
 
-dialogsWidthMin: 260px;
-dialogsWidthMax: 540px;
 dialogsWidthDuration: 120;
 dialogsTextWidthMin: 150px;
 dialogsScroll: ScrollArea(defaultScrollArea) {
diff --git a/Telegram/SourceFiles/dialogs/dialogs_inner_widget.cpp b/Telegram/SourceFiles/dialogs/dialogs_inner_widget.cpp
index d06d66b43..cfe6556cf 100644
--- a/Telegram/SourceFiles/dialogs/dialogs_inner_widget.cpp
+++ b/Telegram/SourceFiles/dialogs/dialogs_inner_widget.cpp
@@ -25,6 +25,7 @@ Copyright (c) 2014-2017 John Preston, https://desktop.telegram.org
 #include "dialogs/dialogs_search_from_controllers.h"
 #include "styles/style_dialogs.h"
 #include "styles/style_chat_helpers.h"
+#include "styles/style_window.h"
 #include "ui/widgets/buttons.h"
 #include "ui/widgets/popup_menu.h"
 #include "data/data_drafts.h"
@@ -959,7 +960,7 @@ void DialogsInner::setSearchedPressed(int pressed) {
 
 void DialogsInner::resizeEvent(QResizeEvent *e) {
 	_addContactLnk->move((width() - _addContactLnk->width()) / 2, (st::noContactsHeight + st::noContactsFont->height) / 2);
-	auto widthForCancelButton = qMax(width() + otherWidth(), st::dialogsWidthMin);
+	auto widthForCancelButton = qMax(width() + otherWidth(), st::columnMinimalWidthLeft);
 	_cancelSearchInPeer->moveToLeft(widthForCancelButton - st::dialogsSearchInSkip - _cancelSearchInPeer->width(), st::searchedBarHeight + (st::dialogsSearchInHeight - st::dialogsCancelSearchInPeer.height) / 2);
 	_cancelSearchFromUser->moveToLeft(widthForCancelButton - st::dialogsSearchInSkip - _cancelSearchFromUser->width(), st::searchedBarHeight + st::dialogsSearchInHeight + st::lineWidth + (st::dialogsSearchInHeight - st::dialogsCancelSearchInPeer.height) / 2);
 }
diff --git a/Telegram/SourceFiles/dialogs/dialogs_widget.cpp b/Telegram/SourceFiles/dialogs/dialogs_widget.cpp
index e11217a91..eca1bdff7 100644
--- a/Telegram/SourceFiles/dialogs/dialogs_widget.cpp
+++ b/Telegram/SourceFiles/dialogs/dialogs_widget.cpp
@@ -23,6 +23,7 @@ Copyright (c) 2014-2017 John Preston, https://desktop.telegram.org
 #include "dialogs/dialogs_inner_widget.h"
 #include "dialogs/dialogs_search_from_controllers.h"
 #include "styles/style_dialogs.h"
+#include "styles/style_window.h"
 #include "ui/widgets/buttons.h"
 #include "ui/widgets/input_fields.h"
 #include "ui/wrap/fade_wrap.h"
@@ -64,7 +65,7 @@ private:
 DialogsWidget::UpdateButton::UpdateButton(QWidget *parent) : RippleButton(parent, st::dialogsUpdateButton.ripple)
 , _text(lang(lng_update_telegram).toUpper())
 , _st(st::dialogsUpdateButton) {
-	resize(st::dialogsWidthMin, _st.height);
+	resize(st::columnMinimalWidthLeft, _st.height);
 }
 
 void DialogsWidget::UpdateButton::onStateChanged(State was, StateChangeSource source) {
@@ -84,7 +85,7 @@ void DialogsWidget::UpdateButton::paintEvent(QPaintEvent *e) {
 	p.setRenderHint(QPainter::TextAntialiasing);
 	p.setPen(isOver() ? _st.overColor : _st.color);
 
-	if (width() >= st::dialogsWidthMin) {
+	if (width() >= st::columnMinimalWidthLeft) {
 		r.setTop(_st.textTop);
 		p.drawText(r, _text, style::al_top);
 	} else {
@@ -221,10 +222,16 @@ void DialogsWidget::startWidthAnimation() {
 		return;
 	}
 	auto scrollGeometry = _scroll->geometry();
-	auto grabGeometry = QRect(scrollGeometry.x(), scrollGeometry.y(), st::dialogsWidthMin, scrollGeometry.height());
+	auto grabGeometry = QRect(
+		scrollGeometry.x(),
+		scrollGeometry.y(),
+		st::columnMinimalWidthLeft,
+		scrollGeometry.height());
 	_scroll->setGeometry(grabGeometry);
 	myEnsureResized(_scroll);
-	auto image = QImage(grabGeometry.size() * cIntRetinaFactor(), QImage::Format_ARGB32_Premultiplied);
+	auto image = QImage(
+		grabGeometry.size() * cIntRetinaFactor(),
+		QImage::Format_ARGB32_Premultiplied);
 	image.setDevicePixelRatio(cRetinaFactor());
 	image.fill(Qt::transparent);
 	_scroll->render(&image, QPoint(0, 0), QRect(QPoint(0, 0), grabGeometry.size()), QWidget::DrawChildren | QWidget::IgnoreMask);
@@ -974,10 +981,10 @@ void DialogsWidget::updateControlsGeometry() {
 		filterAreaTop += st::dialogsForwardHeight;
 	}
 	auto smallLayoutWidth = (st::dialogsPadding.x() + st::dialogsPhotoSize + st::dialogsPadding.x());
-	auto smallLayoutRatio = (width() < st::dialogsWidthMin) ? (st::dialogsWidthMin - width()) / float64(st::dialogsWidthMin - smallLayoutWidth) : 0.;
+	auto smallLayoutRatio = (width() < st::columnMinimalWidthLeft) ? (st::columnMinimalWidthLeft - width()) / float64(st::columnMinimalWidthLeft - smallLayoutWidth) : 0.;
 	auto filterLeft = st::dialogsFilterPadding.x() + _mainMenuToggle->width() + st::dialogsFilterPadding.x();
 	auto filterRight = (Global::LocalPasscode() ? (st::dialogsFilterPadding.x() + _lockUnlock->width()) : st::dialogsFilterSkip) + st::dialogsFilterPadding.x();
-	auto filterWidth = qMax(width(), st::dialogsWidthMin) - filterLeft - filterRight;
+	auto filterWidth = qMax(width(), st::columnMinimalWidthLeft) - filterLeft - filterRight;
 	auto filterAreaHeight = st::dialogsFilterPadding.y() + _mainMenuToggle->height() + st::dialogsFilterPadding.y();
 	auto filterTop = filterAreaTop + (filterAreaHeight - _filter->height()) / 2;
 	filterLeft = anim::interpolate(filterLeft, smallLayoutWidth, smallLayoutRatio);
diff --git a/Telegram/SourceFiles/history/history_message.cpp b/Telegram/SourceFiles/history/history_message.cpp
index c64913dbd..58be62ec0 100644
--- a/Telegram/SourceFiles/history/history_message.cpp
+++ b/Telegram/SourceFiles/history/history_message.cpp
@@ -36,6 +36,7 @@ Copyright (c) 2014-2017 John Preston, https://desktop.telegram.org
 #include "styles/style_dialogs.h"
 #include "styles/style_widgets.h"
 #include "styles/style_history.h"
+#include "styles/style_window.h"
 #include "window/notifications_manager.h"
 #include "observer_peer.h"
 #include "storage/storage_shared_media.h"
@@ -46,7 +47,7 @@ constexpr auto kPinnedMessageTextLimit = 16;
 
 inline void initTextOptions() {
 	_historySrvOptions.dir = _textNameOptions.dir = _textDlgOptions.dir = cLangDir();
-	_textDlgOptions.maxw = st::dialogsWidthMax * 2;
+	_textDlgOptions.maxw = st::columnMaximalWidthLeft * 2;
 }
 
 style::color fromNameFg(int index) {
diff --git a/Telegram/SourceFiles/mainwidget.cpp b/Telegram/SourceFiles/mainwidget.cpp
index e3c6b0253..21eebce69 100644
--- a/Telegram/SourceFiles/mainwidget.cpp
+++ b/Telegram/SourceFiles/mainwidget.cpp
@@ -21,6 +21,7 @@ Copyright (c) 2014-2017 John Preston, https://desktop.telegram.org
 #include "mainwidget.h"
 
 #include <rpl/combine.h>
+#include <rpl/merge.h>
 #include <rpl/flatten_latest.h>
 #include "data/data_photo.h"
 #include "data/data_document.h"
@@ -225,7 +226,8 @@ MainWidget::MainWidget(
 	not_null<Window::Controller*> controller)
 : RpWidget(parent)
 , _controller(controller)
-, _dialogsWidth(st::dialogsWidthMin)
+, _dialogsWidth(st::columnMinimalWidthLeft)
+, _thirdColumnWidth(st::columnMinimalWidthThird)
 , _sideShadow(this)
 , _dialogs(this, _controller)
 , _history(this, _controller)
@@ -262,7 +264,11 @@ MainWidget::MainWidget(
 	subscribe(_controller->dialogsListDisplayForced(), [this](bool) {
 		updateDialogsWidthAnimated();
 	});
-	Auth().data().dialogsWidthRatioChanges()
+	rpl::merge(
+		Auth().data().dialogsWidthRatioChanges()
+			| rpl::map([] { return rpl::empty_value(); }),
+		Auth().data().thirdColumnWidthChanges()
+			| rpl::map([] { return rpl::empty_value(); }))
 		| rpl::start_with_next(
 			[this] { updateControlsGeometry(); },
 			lifetime());
@@ -2773,7 +2779,11 @@ Window::SectionSlideParams MainWidget::prepareShowAnimation(
 
 	auto sectionTop = getMainSectionTop();
 	if (selectingPeer() && Adaptive::OneColumn()) {
-		result.oldContentCache = myGrab(this, QRect(0, sectionTop, _dialogsWidth, height() - sectionTop));
+		result.oldContentCache = myGrab(this, QRect(
+			0,
+			sectionTop,
+			_dialogsWidth,
+			height() - sectionTop));
 	} else if (_mainSection) {
 		result.oldContentCache = _mainSection->grabForShowAnimation(result);
 	} else {
@@ -2785,13 +2795,21 @@ Window::SectionSlideParams MainWidget::prepareShowAnimation(
 			_history->grabStart();
 		}
 		if (Adaptive::OneColumn()) {
-			result.oldContentCache = myGrab(this, QRect(0, sectionTop, _dialogsWidth, height() - sectionTop));
+			result.oldContentCache = myGrab(this, QRect(
+				0,
+				sectionTop,
+				_dialogsWidth,
+				height() - sectionTop));
 		} else {
 			_sideShadow->hide();
 			if (_thirdShadow) {
 				_thirdShadow->hide();
 			}
-			result.oldContentCache = myGrab(this, QRect(_dialogsWidth, sectionTop, width() - _dialogsWidth, height() - sectionTop));
+			result.oldContentCache = myGrab(this, QRect(
+				_dialogsWidth,
+				sectionTop,
+				width() - _dialogsWidth,
+				height() - sectionTop));
 			_sideShadow->show();
 			if (_thirdShadow) {
 				_thirdShadow->show();
@@ -3118,13 +3136,21 @@ QPixmap MainWidget::grabForShowAnimation(const Window::SectionSlideParams &param
 
 	auto sectionTop = getMainSectionTop();
 	if (Adaptive::OneColumn()) {
-		result = myGrab(this, QRect(0, sectionTop, _dialogsWidth, height() - sectionTop));
+		result = myGrab(this, QRect(
+			0,
+			sectionTop,
+			_dialogsWidth,
+			height() - sectionTop));
 	} else {
 		_sideShadow->hide();
 		if (_thirdShadow) {
 			_thirdShadow->hide();
 		}
-		result = myGrab(this, QRect(_dialogsWidth, sectionTop, width() - _dialogsWidth, height() - sectionTop));
+		result = myGrab(this, QRect(
+			_dialogsWidth,
+			sectionTop,
+			width() - _dialogsWidth,
+			height() - sectionTop));
 		_sideShadow->show();
 		if (_thirdShadow) {
 			_thirdShadow->show();
@@ -3423,11 +3449,9 @@ void MainWidget::updateControlsGeometry() {
 		_history->setGeometry(mainSectionGeometry);
 		if (_hider) _hider->setGeometry(0, 0, dialogsWidth, height());
 	} else {
-		auto thirdSectionWidth = _thirdSection ? _thirdSection->width() : 0;
+		auto thirdSectionWidth = _thirdSection ? _thirdColumnWidth : 0;
 		if (_thirdSection) {
 			auto thirdSectionTop = getThirdSectionTop();
-			accumulate_min(thirdSectionWidth, width() - st::columnMinimalWidthMain - st::columnMinimalWidthLeft);
-			accumulate_max(thirdSectionWidth, st::columnMinimalWidthThird);
 			_thirdSection->setGeometry(
 				width() - thirdSectionWidth,
 				thirdSectionTop,
@@ -3517,14 +3541,16 @@ void MainWidget::ensureFirstColumnResizeAreaCreated() {
 	}
 	auto moveLeftCallback = [=](int globalLeft) {
 		auto newWidth = globalLeft - mapToGlobal(QPoint(0, 0)).x();
-		auto newRatio = (newWidth < st::dialogsWidthMin / 2)
+		auto newRatio = (newWidth < st::columnMinimalWidthLeft / 2)
 			? 0.
 			: float64(newWidth) / width();
 		Auth().data().setDialogsWidthRatio(newRatio);
 	};
 	auto moveFinishedCallback = [=] {
-		if (!Adaptive::OneColumn()
-			&& Auth().data().dialogsWidthRatio() > 0) {
+		if (Adaptive::OneColumn()) {
+			return;
+		}
+		if (Auth().data().dialogsWidthRatio() > 0) {
 			Auth().data().setDialogsWidthRatio(
 				float64(_dialogsWidth) / width());
 		}
@@ -3541,9 +3567,18 @@ void MainWidget::ensureThirdColumnResizeAreaCreated() {
 		return;
 	}
 	auto moveLeftCallback = [=](int globalLeft) {
+		auto newWidth = mapToGlobal(QPoint(width(), 0)).x() - globalLeft;
+		Auth().data().setThirdColumnWidth(newWidth);
 	};
 	auto moveFinishedCallback = [=] {
-
+		if (!Adaptive::ThreeColumn() || !_thirdSection) {
+			return;
+		}
+		Auth().data().setThirdColumnWidth(snap(
+			Auth().data().thirdColumnWidth(),
+			st::columnMinimalWidthThird,
+			st::columnMaximalWidthThird));
+		Local::writeUserSettings();
 	};
 	createResizeArea(
 		_thirdColumnResizeArea,
@@ -3739,6 +3774,7 @@ void MainWidget::updateWindowAdaptiveLayout() {
 	_dialogsWidth = useSmallColumnWidth
 		? _controller->dialogsSmallColumnWidth()
 		: layout.dialogsWidth;
+	_thirdColumnWidth = layout.thirdWidth;
 	if (layout.windowLayout != Global::AdaptiveWindowLayout()) {
 		Global::SetAdaptiveWindowLayout(layout.windowLayout);
 		Adaptive::Changed().notify(true);
diff --git a/Telegram/SourceFiles/mainwidget.h b/Telegram/SourceFiles/mainwidget.h
index 2502f73bd..036622f3f 100644
--- a/Telegram/SourceFiles/mainwidget.h
+++ b/Telegram/SourceFiles/mainwidget.h
@@ -583,7 +583,8 @@ private:
 	bool _showBack = false;
 	QPixmap _cacheUnder, _cacheOver;
 
-	int _dialogsWidth;
+	int _dialogsWidth = 0;
+	int _thirdColumnWidth = 0;
 	Animation _a_dialogsWidth;
 
 	object_ptr<Ui::PlainShadow> _sideShadow;
diff --git a/Telegram/SourceFiles/window/window.style b/Telegram/SourceFiles/window/window.style
index 1b7d83d85..c1c1114b2 100644
--- a/Telegram/SourceFiles/window/window.style
+++ b/Telegram/SourceFiles/window/window.style
@@ -31,8 +31,10 @@ windowShadow: icon {{ "window_shadow", windowShadowFg }};
 windowShadowShift: 1px;
 
 columnMinimalWidthLeft: 260px;
+columnMaximalWidthLeft: 540px;
 columnMinimalWidthMain: 380px;
 columnMinimalWidthThird: 292px;//345px;
+columnMaximalWidthThird: 345px;
 
 adaptiveChatWideWidth: 880px;
 
diff --git a/Telegram/SourceFiles/window/window_controller.cpp b/Telegram/SourceFiles/window/window_controller.cpp
index 37a5d639e..c48734741 100644
--- a/Telegram/SourceFiles/window/window_controller.cpp
+++ b/Telegram/SourceFiles/window/window_controller.cpp
@@ -108,23 +108,63 @@ Controller::ColumnLayout Controller::computeColumnLayout() const {
 		dialogsWidth = chatWidth = bodyWidth;
 	} else if (useNormalLayout()) {
 		layout = Adaptive::WindowLayout::Normal;
-		dialogsWidth = qRound(bodyWidth * Auth().data().dialogsWidthRatio());
-		accumulate_max(dialogsWidth, st::columnMinimalWidthLeft);
+		dialogsWidth = countDialogsWidthFromRatio(bodyWidth);
 		accumulate_min(dialogsWidth, bodyWidth - st::columnMinimalWidthMain);
 		chatWidth = bodyWidth - dialogsWidth;
 	} else {
 		layout = Adaptive::WindowLayout::ThreeColumn;
-		dialogsWidth = qRound(bodyWidth * Auth().data().dialogsWidthRatio());
-		accumulate_max(dialogsWidth, st::columnMinimalWidthLeft);
-		thirdWidth = st::columnMinimalWidthThird;
-		accumulate_min(
+		dialogsWidth = countDialogsWidthFromRatio(bodyWidth);
+		thirdWidth = countThirdColumnWidthFromRatio(bodyWidth);
+		auto shrink = shrinkDialogsAndThirdColumns(
 			dialogsWidth,
-			bodyWidth - thirdWidth - st::columnMinimalWidthMain);
+			thirdWidth,
+			bodyWidth);
+		dialogsWidth = shrink.dialogsWidth;
+		thirdWidth = shrink.thirdWidth;
+
 		chatWidth = bodyWidth - dialogsWidth - thirdWidth;
 	}
 	return { bodyWidth, dialogsWidth, chatWidth, thirdWidth, layout };
 }
 
+int Controller::countDialogsWidthFromRatio(int bodyWidth) const {
+	auto result = qRound(bodyWidth * Auth().data().dialogsWidthRatio());
+	accumulate_max(result, st::columnMinimalWidthLeft);
+	accumulate_min(result, st::columnMaximalWidthLeft);
+	return result;
+}
+
+int Controller::countThirdColumnWidthFromRatio(int bodyWidth) const {
+	auto result = Auth().data().thirdColumnWidth();
+	accumulate_max(result, st::columnMinimalWidthThird);
+	accumulate_min(result, st::columnMaximalWidthThird);
+	return result;
+}
+
+Controller::ShrinkResult Controller::shrinkDialogsAndThirdColumns(
+		int dialogsWidth,
+		int thirdWidth,
+		int bodyWidth) const {
+	auto chatWidth = st::columnMinimalWidthMain;
+	if (dialogsWidth + thirdWidth + chatWidth <= bodyWidth) {
+		return { dialogsWidth, thirdWidth };
+	}
+	auto thirdWidthNew = ((bodyWidth - chatWidth) * thirdWidth)
+		/ (dialogsWidth + thirdWidth);
+	auto dialogsWidthNew = ((bodyWidth - chatWidth) * dialogsWidth)
+		/ (dialogsWidth + thirdWidth);
+	if (thirdWidthNew < st::columnMinimalWidthThird) {
+		thirdWidthNew = st::columnMinimalWidthThird;
+		dialogsWidthNew = bodyWidth - thirdWidthNew - chatWidth;
+		Assert(dialogsWidthNew >= st::columnMinimalWidthLeft);
+	} else if (dialogsWidthNew < st::columnMinimalWidthLeft) {
+		dialogsWidthNew = st::columnMinimalWidthLeft;
+		thirdWidthNew = bodyWidth - dialogsWidthNew - chatWidth;
+		Assert(thirdWidthNew >= st::columnMinimalWidthThird);
+	}
+	return { dialogsWidthNew, thirdWidthNew };
+}
+
 bool Controller::canShowThirdSection() const {
 	auto currentLayout = computeColumnLayout();
 	auto extendBy = minimalThreeColumnWidth()
diff --git a/Telegram/SourceFiles/window/window_controller.h b/Telegram/SourceFiles/window/window_controller.h
index 7f10978ad..7f36f8e92 100644
--- a/Telegram/SourceFiles/window/window_controller.h
+++ b/Telegram/SourceFiles/window/window_controller.h
@@ -189,6 +189,16 @@ public:
 private:
 	int minimalThreeColumnWidth() const;
 	not_null<MainWidget*> chats() const;
+	int countDialogsWidthFromRatio(int bodyWidth) const;
+	int countThirdColumnWidthFromRatio(int bodyWidth) const;
+	struct ShrinkResult {
+		int dialogsWidth;
+		int thirdWidth;
+	};
+	ShrinkResult shrinkDialogsAndThirdColumns(
+		int dialogsWidth,
+		int thirdWidth,
+		int bodyWidth) const;
 
 	not_null<MainWindow*> _window;