Switch layout to Normal in a wide enough window.

A lot of people didn't know how to bring the dialogs column back
after it was gone in a wide single column MainWindow.

Now we switch to a two column layout if the window allows it,
preserving the emoji / stickers / GIFs section in case it is shown.

Telegram/SourceFiles/historywidget.cpp

@@ -3735,8 +3735,12 @@ void HistoryWidget::updateTabbedSelectorSectionShown() {
 	orderWidgets();
 }
 
+int HistoryWidget::tabbedSelectorSectionWidth() const {
+	return st::emojiPanWidth;
+}
+
 int HistoryWidget::minimalWidthForTabbedSelectorSection() const {
-	return st::windowMinWidth + st::emojiPanWidth;
+	return st::windowMinWidth + tabbedSelectorSectionWidth();
 }
 
 void HistoryWidget::toggleTabbedSelectorMode() {

Telegram/SourceFiles/historywidget.h

@@ -200,6 +200,8 @@ public:
 	void unreadCountChanged(History *history);
 
 	QRect historyRect() const;
+	int tabbedSelectorSectionWidth() const;
+	int minimalWidthForTabbedSelectorSection() const;
 
 	void updateSendAction(History *history, SendAction::Type type, int32 progress = 0);
 	void cancelSendAction(History *history, SendAction::Type type);
@@ -480,7 +482,6 @@ private:
 	void toggleTabbedSelectorMode();
 	void updateTabbedSelectorSectionShown();
 	void recountChatWidth();
-	int minimalWidthForTabbedSelectorSection() const;
 	void setReportSpamStatus(DBIPeerReportSpamStatus status);
 
 	void animationCallback();

Telegram/SourceFiles/mainwidget.cpp

@@ -3160,6 +3160,7 @@ bool MainWidget::eventFilter(QObject *o, QEvent *e) {
 			Local::writeUserSettings();
 		} else if (e->type() == QEvent::MouseMove && _resizingSide) {
 			auto newWidth = mouseLeft() - _resizingSideShift;
+			accumulate_max(newWidth, _controller->dialogsSmallColumnWidth());
 			_controller->dialogsWidthRatio().set(float64(newWidth) / width(), true);
 		}
 	} else if (e->type() == QEvent::FocusIn) {
@@ -3191,6 +3192,19 @@ void MainWidget::handleAdaptiveLayoutUpdate() {
 
 void MainWidget::updateWindowAdaptiveLayout() {
 	auto layout = _controller->computeColumnLayout();
+	if (layout.windowLayout == Adaptive::WindowLayout::OneColumn) {
+		auto chatWidth = layout.dialogsWidth;
+		if (AuthSession::Current().data().tabbedSelectorSectionEnabled()
+			&& chatWidth >= _history->minimalWidthForTabbedSelectorSection()) {
+			chatWidth -= _history->tabbedSelectorSectionWidth();
+		}
+		if (chatWidth >= st::dialogsWidthMin + st::windowMinWidth) {
+			// Switch layout back to normal in a wide enough window.
+			layout.windowLayout = Adaptive::WindowLayout::Normal;
+			layout.dialogsWidth = st::dialogsWidthMin;
+			_controller->dialogsWidthRatio().set(float64(layout.dialogsWidth) / layout.bodyWidth, true);
+		}
+	}
 	_dialogsWidth = layout.dialogsWidth;
 	if (layout.windowLayout != Global::AdaptiveWindowLayout()) {
 		Global::SetAdaptiveWindowLayout(layout.windowLayout);

Telegram/SourceFiles/window/window_controller.cpp

@@ -53,6 +53,10 @@ bool Controller::isGifPausedAtLeastFor(GifPauseReason reason) const {
 	return (static_cast<int>(_gifPauseReasons) >= 2 * static_cast<int>(reason)) || !window()->isActive();
 }
 
+int Controller::dialogsSmallColumnWidth() const {
+	return st::dialogsPadding.x() + st::dialogsPhotoSize + st::dialogsPadding.x();
+}
+
 Controller::ColumnLayout Controller::computeColumnLayout() {
 	auto layout = Adaptive::WindowLayout::OneColumn;
 
@@ -94,7 +98,7 @@ Controller::ColumnLayout Controller::computeColumnLayout() {
 		if (forceWideDialogs()) {
 			dialogsWidth = st::dialogsWidthMin;
 		} else {
-			dialogsWidth = st::dialogsPadding.x() + st::dialogsPhotoSize + st::dialogsPadding.x();
+			dialogsWidth = dialogsSmallColumnWidth();
 		}
 	} else {
 		layout = Adaptive::WindowLayout::Normal;

Telegram/SourceFiles/window/window_controller.h

@@ -72,6 +72,7 @@ public:
 		Adaptive::WindowLayout windowLayout;
 	};
 	ColumnLayout computeColumnLayout();
+	int dialogsSmallColumnWidth() const;
 	bool provideChatWidth(int requestedWidth);
 
 	base::Variable<float64> &dialogsWidthRatio() {