Implemented showing and hiding of side bar when it does not contain any visible tab

src/AutoHideDockContainer.cpp

@@ -107,6 +107,7 @@ struct AutoHideDockContainerPrivate
 	QBoxLayout* Layout;
 	CResizeHandle* ResizeHandle = nullptr;
 	QSize Size; // creates invalid size
+	CDockWidgetSideTab* SideTab = nullptr;
 
 	/**
 	 * Private data constructor

src/AutoHideDockContainer.h

@@ -70,12 +70,14 @@ public:
 	/**
 	 * Create Auto Hide widget with a dock manager
 	 */
-    CAutoHideDockContainer(CDockManager* DockManager, SideBarLocation area, CDockContainerWidget* parent);
+    CAutoHideDockContainer(CDockManager* DockManager, SideBarLocation area,
+    	CDockContainerWidget* parent);
 
     /**
 	 * Create Auto Hide widget with the given dock widget
 	 */
-	CAutoHideDockContainer(CDockWidget* DockWidget, SideBarLocation area, CDockContainerWidget* parent);
+	CAutoHideDockContainer(CDockWidget* DockWidget, SideBarLocation area,
+		CDockContainerWidget* parent);
 
 	/**
 	 * Virtual Destructor

src/DockWidget.cpp

@@ -79,7 +79,6 @@ struct DockWidgetPrivate
 	QBoxLayout* Layout = nullptr;
 	QWidget* Widget = nullptr;
 	CDockWidgetTab* TabWidget = nullptr;
-	CDockWidgetSideTab* SideTabWidget = nullptr;
 	CDockWidget::DockWidgetFeatures Features = CDockWidget::DefaultDockWidgetFeatures;
 	CDockManager* DockManager = nullptr;
 	CDockAreaWidget* DockArea = nullptr;
@@ -97,6 +96,7 @@ struct DockWidgetPrivate
 	WidgetFactory* Factory = nullptr;
 	double DefaultAutoHideDockProportion = 0.25;
 	CDockWidget::eAutoHideInsertOrder AutoHideInsertOrder = CDockWidget::Last;
+	QPointer<CDockWidgetSideTab> SideTabWidget;
 	
 	/**
 	 * Private data constructor
@@ -246,6 +246,8 @@ void DockWidgetPrivate::updateParentDockArea()
 	}
 }
 
+
+//============================================================================
 void DockWidgetPrivate::closeAutoHideDockWidgetsIfNeeded()
 {
 	if (_this->dockContainer() && _this->dockContainer()->openedDockWidgets().isEmpty() && !_this->dockManager()->isRestoringState())

src/SideTabBar.cpp

@@ -113,6 +113,7 @@ CSideTabBar::CSideTabBar(CDockContainerWidget* parent, SideBarLocation area) :
 //============================================================================
 CSideTabBar::~CSideTabBar() 
 {
+	qDebug() << "~CSideTabBar() ";
 	// The SideTabeBar is not the owner of the tabs and to prevent deletion
 	// we set the parent here to nullptr to remove it from the children
 	auto Tabs = findChildren<CDockWidgetSideTab*>(QString(), Qt::FindDirectChildrenOnly);
@@ -127,6 +128,7 @@ CSideTabBar::~CSideTabBar()
 //============================================================================
 void CSideTabBar::insertSideTab(int Index, CDockWidgetSideTab* SideTab)
 {
+	SideTab->installEventFilter(this);
     d->TabsLayout->insertWidget(Index, SideTab);
     SideTab->setSideTabBar(this);
     show();
@@ -166,6 +168,7 @@ void CSideTabBar::removeDockWidget(CDockWidget* DockWidget)
 void CSideTabBar::removeSideTab(CDockWidgetSideTab* SideTab)
 {
 	qDebug() << "CSideTabBar::removeSideTab " << SideTab->text();
+	SideTab->removeEventFilter(this);
     d->TabsLayout->removeWidget(SideTab);
     if (d->TabsLayout->isEmpty())
     {
@@ -174,6 +177,65 @@ void CSideTabBar::removeSideTab(CDockWidgetSideTab* SideTab)
 }
 
 
+//============================================================================
+bool CSideTabBar::event(QEvent* e)
+{
+	qDebug() << e;
+	switch (e->type())
+	{
+	case QEvent::ChildRemoved:
+		if (d->TabsLayout->isEmpty())
+		{
+			hide();
+		}
+		break;
+
+	case QEvent::Resize:
+		if (d->TabsLayout->count())
+		{
+			auto ev = static_cast<QResizeEvent*>(e);
+			auto Tab = tabAt(0);
+			int Size = d->isHorizontal() ? ev->size().height() : ev->size().width();
+			int TabSize = d->isHorizontal() ? Tab->size().height() : Tab->size().width();
+			// If the size of the side bar is less than the size of the first tab
+			// then there are no visible tabs in this side bar. This check will
+			// fail if someone will force a very big border via CSS!!
+			if (Size < TabSize)
+			{
+				hide();
+			}
+		}
+		else
+		{
+			hide();
+		}
+		break;
+
+	default:
+		break;
+	}
+	return Super::event(e);
+}
+
+
+//============================================================================
+bool CSideTabBar::eventFilter(QObject *watched, QEvent *event)
+{
+	if (event->type() != QEvent::ShowToParent)
+	{
+		return false;
+	}
+
+	// As soon as on tab is shhown, we need to show the side tab bar
+	auto Tab = qobject_cast<CDockWidgetSideTab*>(watched);
+	if (Tab)
+	{
+		show();
+	}
+	return false;
+}
+
+
 //============================================================================
 void CSideTabBar::paintEvent(QPaintEvent* event)
 {
@@ -212,4 +274,5 @@ SideBarLocation CSideTabBar::sideTabBarArea() const
 {
 	return d->SideTabArea;
 }
+
 }

src/SideTabBar.h

@@ -55,7 +55,9 @@ private:
 	friend class DockWidgetSideTab;
 
 protected:
-    void paintEvent(QPaintEvent* event) override;
+    virtual void paintEvent(QPaintEvent* event) override;
+	virtual bool event(QEvent* e) override;
+	virtual bool eventFilter(QObject *watched, QEvent *event) override;
 
 public:
     using Super = QFrame;