Fixed build for Qt5.5.1

adding linux src files to CMake

.cproject

@@ -71,15 +71,6 @@
 	</storageModule>
 	<storageModule moduleId="org.eclipse.cdt.core.LanguageSettingsProviders"/>
 	<storageModule moduleId="refreshScope"/>
-	<storageModule moduleId="scannerConfiguration">
-		<autodiscovery enabled="true" problemReportingEnabled="true" selectedProfileId=""/>
-		<scannerConfigBuildInfo instanceId="cdt.managedbuild.toolchain.gnu.mingw.base.1119687795;cdt.managedbuild.toolchain.gnu.mingw.base.1119687795.1949777584;cdt.managedbuild.tool.gnu.cpp.compiler.mingw.base.1947822681;cdt.managedbuild.tool.gnu.cpp.compiler.input.1318830536">
-			<autodiscovery enabled="false" problemReportingEnabled="true" selectedProfileId="org.eclipse.cdt.make.core.GCCStandardMakePerFileProfile"/>
-		</scannerConfigBuildInfo>
-		<scannerConfigBuildInfo instanceId="cdt.managedbuild.toolchain.gnu.mingw.base.1119687795;cdt.managedbuild.toolchain.gnu.mingw.base.1119687795.1949777584;cdt.managedbuild.tool.gnu.c.compiler.mingw.base.389117097;cdt.managedbuild.tool.gnu.c.compiler.input.1568363924">
-			<autodiscovery enabled="true" problemReportingEnabled="true" selectedProfileId=""/>
-		</scannerConfigBuildInfo>
-	</storageModule>
 	<storageModule moduleId="org.eclipse.cdt.make.core.buildtargets">
 		<buildTargets>
 			<target name="Build all" path=" build" targetID="org.eclipse.cdt.build.MakeTargetBuilder">
@@ -356,4 +347,13 @@
 			</target>
 		</buildTargets>
 	</storageModule>
+	<storageModule moduleId="scannerConfiguration">
+		<autodiscovery enabled="true" problemReportingEnabled="true" selectedProfileId=""/>
+		<scannerConfigBuildInfo instanceId="cdt.managedbuild.toolchain.gnu.mingw.base.1119687795;cdt.managedbuild.toolchain.gnu.mingw.base.1119687795.1949777584;cdt.managedbuild.tool.gnu.cpp.compiler.mingw.base.1947822681;cdt.managedbuild.tool.gnu.cpp.compiler.input.1318830536">
+			<autodiscovery enabled="false" problemReportingEnabled="true" selectedProfileId="org.eclipse.cdt.make.core.GCCStandardMakePerFileProfile"/>
+		</scannerConfigBuildInfo>
+		<scannerConfigBuildInfo instanceId="cdt.managedbuild.toolchain.gnu.mingw.base.1119687795;cdt.managedbuild.toolchain.gnu.mingw.base.1119687795.1949777584;cdt.managedbuild.tool.gnu.c.compiler.mingw.base.389117097;cdt.managedbuild.tool.gnu.c.compiler.input.1568363924">
+			<autodiscovery enabled="true" problemReportingEnabled="true" selectedProfileId=""/>
+		</scannerConfigBuildInfo>
+	</storageModule>
 </cproject>

CMakeLists.txt

@@ -40,6 +40,7 @@ set(ads_SRCS
     src/ElidingLabel.cpp
     src/FloatingDockContainer.cpp
     src/ads.qrc
+    src/linux/FloatingWidgetTitleBar.cpp
 )
 set(ads_INSTALL_INCLUDE 
     src/ads_globals.h
@@ -54,6 +55,7 @@ set(ads_INSTALL_INCLUDE
     src/DockWidgetTab.h
     src/ElidingLabel.h
     src/FloatingDockContainer.h
+    src/linux/FloatingWidgetTitleBar.h
 )
 if("${CMAKE_SIZEOF_VOID_P}" STREQUAL "4")
     set(ads_PlatformDir "x86")

README.md

@@ -1,6 +1,7 @@
 # Advanced Docking System for Qt 
 [![Build Status](https://travis-ci.org/githubuser0xFFFF/Qt-Advanced-Docking-System.svg?branch=master)](https://travis-ci.org/githubuser0xFFFF/Qt-Advanced-Docking-System)
 [![Build status](https://ci.appveyor.com/api/projects/status/qcfb3cy932jw9mpy/branch/master?svg=true)](https://ci.appveyor.com/project/githubuser0xFFFF/qt-advanced-docking-system/branch/master)
+[![License: LGPL v2.1](https://img.shields.io/badge/License-LGPL%20v2.1-blue.svg)](gnu-lgpl-v2.1.md)
 
 
 
@@ -60,9 +61,22 @@ main window layout.
 ![Perspective](doc/perspectives_dark.png)
 
 ## Tested Compatible Environments
-- Windows 10 [![Build status](https://ci.appveyor.com/api/projects/status/qcfb3cy932jw9mpy/branch/master?svg=true)](https://ci.appveyor.com/project/githubuser0xFFFF/qt-advanced-docking-system/branch/master)
-- Ubuntu [![Build Status](https://travis-ci.org/githubuser0xFFFF/Qt-Advanced-Docking-System.svg?branch=master)](https://travis-ci.org/githubuser0xFFFF/Qt-Advanced-Docking-System)
-- macOS [![Build Status](https://travis-ci.org/githubuser0xFFFF/Qt-Advanced-Docking-System.svg?branch=master)](https://travis-ci.org/githubuser0xFFFF/Qt-Advanced-Docking-System)
+### Windows
+Windows 10 [![Build status](https://ci.appveyor.com/api/projects/status/qcfb3cy932jw9mpy/branch/master?svg=true)](https://ci.appveyor.com/project/githubuser0xFFFF/qt-advanced-docking-system/branch/master)
+
+The library was developed on and for Windows. It is used in a commercial Windows application and is therefore constantly tested.
+
+### macOS
+macOS [![Build Status](https://travis-ci.org/githubuser0xFFFF/Qt-Advanced-Docking-System.svg?branch=master)](https://travis-ci.org/githubuser0xFFFF/Qt-Advanced-Docking-System)
+
+The application can be compiled for macOS. A user reported, that the library works on macOS. If have not tested it.
+
+### Linux
+Ubuntu [![Build Status](https://travis-ci.org/githubuser0xFFFF/Qt-Advanced-Docking-System.svg?branch=master)](https://travis-ci.org/githubuser0xFFFF/Qt-Advanced-Docking-System)
+
+The application can be compiled for Linux and has been developed and tested with **Kubuntu 18.04**.
+
+![Advanced Docking on Linux](doc/linux_kubuntu_1804.png)
 
 ## Build
 Open the `ads.pro` with QtCreator and start the build, that's it.
@@ -144,5 +158,6 @@ MainWindow::~MainWindow()
 - Manuel Freiholz 
 
 ## License information
+[![License: LGPL v2.1](https://img.shields.io/badge/License-LGPL%20v2.1-blue.svg)](gnu-lgpl-v2.1.md)
 This project uses the [LGPLv2.1 license](gnu-lgpl-v2.1.md)
 

demo/CMakeLists.txt

@@ -23,7 +23,7 @@ set(CMAKE_INCLUDE_CURRENT_DIR ON)
 set(ads_demo_SRCS
     main.cpp
     MainWindow.cpp
-    MainWindow.ui
+    mainwindow.ui
     main.qrc
 )
 add_executable(AdvancedDockingSystemDemo WIN32 ${ads_demo_SRCS})

demo/MainWindow.cpp

@@ -88,6 +88,32 @@ static ads::CDockWidget* createLongTextLabelDockWidget(QMenu* ViewMenu)
 }
 
 
+/**
+ * Function returns a features string with closable (c), movable (m) and floatable (f)
+ * features. i.e. The following string is for a not closable but movable and floatable
+ * widget: c- m+ f+
+ */
+static QString featuresString(ads::CDockWidget* DockWidget)
+{
+	auto f = DockWidget->features();
+	return QString("c%1 m%2 f%3")
+		.arg(f.testFlag(ads::CDockWidget::DockWidgetClosable) ? "+" : "-")
+		.arg(f.testFlag(ads::CDockWidget::DockWidgetMovable) ? "+" : "-")
+		.arg(f.testFlag(ads::CDockWidget::DockWidgetFloatable) ? "+" : "-");
+}
+
+
+/**
+ * Appends the string returned by featuresString() to the window title of
+ * the given DockWidget
+ */
+static void appendFeaturStringToWindowTitle(ads::CDockWidget* DockWidget)
+{
+	DockWidget->setWindowTitle(DockWidget->windowTitle()
+		+  QString(" (%1)").arg(featuresString(DockWidget)));
+}
+
+
 //============================================================================
 static ads::CDockWidget* createCalendarDockWidget(QMenu* ViewMenu)
 {
@@ -110,7 +136,8 @@ static ads::CDockWidget* createFileSystemTreeDockWidget(QMenu* ViewMenu)
 	QFileSystemModel* m = new QFileSystemModel(w);
 	m->setRootPath(QDir::currentPath());
 	w->setModel(m);
-	ads::CDockWidget* DockWidget = new ads::CDockWidget(QString("Filesystem %1").arg(FileSystemCount++));
+	ads::CDockWidget* DockWidget = new ads::CDockWidget(QString("Filesystem %1")
+		.arg(FileSystemCount++));
 	DockWidget->setWidget(w);
 	ViewMenu->addAction(DockWidget->toggleViewAction());
     return DockWidget;
@@ -185,6 +212,8 @@ void MainWindowPrivate::createContent()
 	ToolBar->addAction(ui.actionSaveState);
 	ToolBar->addAction(ui.actionRestoreState);
 	FileSystemWidget->setFeature(ads::CDockWidget::DockWidgetMovable, false);
+	FileSystemWidget->setFeature(ads::CDockWidget::DockWidgetFloatable, false);
+	appendFeaturStringToWindowTitle(FileSystemWidget);
 	auto TopDockArea = DockManager->addDockWidget(ads::TopDockWidgetArea, FileSystemWidget);
 	DockWidget = createCalendarDockWidget(ViewMenu);
 	DockWidget->setFeature(ads::CDockWidget::DockWidgetClosable, false);
@@ -282,7 +311,7 @@ CMainWindow::CMainWindow(QWidget *parent) :
 
 	d->createContent();
 	// Default window geometry
-	resize(800, 600);
+    resize(1280, 720);
 
 	d->restoreState();
 	d->restorePerspectives();

src/DockAreaTabBar.cpp

@@ -205,6 +205,13 @@ void CDockAreaTabBar::mouseMoveEvent(QMouseEvent* ev)
 		return;
 	}
 
+	// If one single dock widget in this area is not floatable then the whole
+	// area is not floatable
+	if (!d->DockArea->features().testFlag(CDockWidget::DockWidgetFloatable))
+	{
+		return;
+	}
+
 	int DragDistance = (d->DragStartMousePos - ev->pos()).manhattanLength();
 	if (DragDistance >= CDockManager::startDragDistance())
 	{
@@ -228,6 +235,11 @@ void CDockAreaTabBar::mouseDoubleClickEvent(QMouseEvent *event)
 	{
 		return;
 	}
+
+	if (!d->DockArea->features().testFlag(CDockWidget::DockWidgetFloatable))
+	{
+		return;
+	}
 	makeAreaFloating(event->pos(), DraggingInactive);
 }
 
@@ -238,7 +250,7 @@ CFloatingDockContainer* CDockAreaTabBar::makeAreaFloating(const QPoint& Offset,
 {
 	QSize Size = d->DockArea->size();
 	CFloatingDockContainer* FloatingWidget = new CFloatingDockContainer(d->DockArea);
-	FloatingWidget->startFloating(Offset, Size, DragState);
+    FloatingWidget->startFloating(Offset, Size, DragState, nullptr);
 	auto TopLevelDockWidget = FloatingWidget->topLevelDockWidget();
 	if (TopLevelDockWidget)
 	{

src/DockAreaTitleBar.cpp

@@ -97,6 +97,23 @@ struct DockAreaTitleBarPrivate
 	{
 		return DockArea->dockManager()->configFlags().testFlag(Flag);
 	}
+
+    /**
+     * Helper class to set title bar button icons depending on operating system
+     * and to avoid duplicated code
+     */
+    void setTitleBarButtonIcon(tTileBarButton* Button, QStyle::StandardPixmap StandarPixmap)
+    {
+    #ifdef Q_OS_LINUX
+        Button->setIcon(_this->style()->standardIcon(StandarPixmap));
+    #else
+        QIcon Icon;
+        QPixmap normalPixmap = _this->style()->standardPixmap(StandarPixmap, 0, Button);
+        Icon.addPixmap(internal::createTransparentPixmap(normalPixmap, 0.25), QIcon::Disabled);
+        Icon.addPixmap(normalPixmap, QIcon::Normal);
+        Button->setIcon(Icon);
+    #endif
+    }
 };// struct DockAreaTitleBarPrivate
 
 
@@ -112,12 +129,12 @@ DockAreaTitleBarPrivate::DockAreaTitleBarPrivate(CDockAreaTitleBar* _public) :
 //============================================================================
 void DockAreaTitleBarPrivate::createButtons()
 {
+    // Tabs menu button
 	TabsMenuButton = new tTileBarButton();
 	TabsMenuButton->setObjectName("tabsMenuButton");
 	TabsMenuButton->setAutoRaise(true);
 	TabsMenuButton->setPopupMode(QToolButton::InstantPopup);
-	TabsMenuButton->setIcon(_this->style()->standardIcon(QStyle::SP_TitleBarUnshadeButton));
-
+    setTitleBarButtonIcon(TabsMenuButton, QStyle::SP_TitleBarUnshadeButton);
 	QMenu* TabsMenu = new QMenu(TabsMenuButton);
 	#ifndef QT_NO_TOOLTIP
 	TabsMenu->setToolTipsVisible(true);
@@ -132,6 +149,7 @@ void DockAreaTitleBarPrivate::createButtons()
 	_this->connect(TabsMenuButton->menu(), SIGNAL(triggered(QAction*)),
 		SLOT(onTabsMenuActionTriggered(QAction*)));
 
+
 	// Undock button
 	UndockButton = new tTileBarButton();
 	UndockButton->setObjectName("undockButton");
@@ -139,22 +157,17 @@ void DockAreaTitleBarPrivate::createButtons()
 	#ifndef QT_NO_TOOLTIP
 	UndockButton->setToolTip(QObject::tr("Detach Group"));
 	#endif
-	UndockButton->setIcon(_this->style()->standardIcon(QStyle::SP_TitleBarNormalButton));
-	UndockButton->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Expanding);
+    setTitleBarButtonIcon(UndockButton, QStyle::SP_TitleBarNormalButton);
+    UndockButton->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Expanding);
 	TopLayout->addWidget(UndockButton, 0);
 	_this->connect(UndockButton, SIGNAL(clicked()), SLOT(onUndockButtonClicked()));
 
+
+    // Close button
 	CloseButton = new tTileBarButton();
 	CloseButton->setObjectName("closeButton");
 	CloseButton->setAutoRaise(true);
-
-	// The standard icons do not look good on high DPI screens
-	QIcon CloseIcon =  _this->style()->standardIcon(QStyle::SP_TitleBarCloseButton);
-	QPixmap normalPixmap = _this->style()->standardPixmap(QStyle::SP_TitleBarCloseButton, 0, CloseButton);
-	QPixmap disabledPixmap = internal::createTransparentPixmap(normalPixmap, 0.25);
-	CloseIcon.addPixmap(disabledPixmap, QIcon::Disabled);
-
-	CloseButton->setIcon(CloseIcon);
+    setTitleBarButtonIcon(CloseButton, QStyle::SP_TitleBarCloseButton);
 	#ifndef QT_NO_TOOLTIP
 	if (testConfigFlag(CDockManager::DockAreaCloseButtonClosesTab))
 	{
@@ -166,6 +179,7 @@ void DockAreaTitleBarPrivate::createButtons()
 	}
 	#endif
 	CloseButton->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Expanding);
+	CloseButton->setIconSize(QSize(16, 16));
 	TopLayout->addWidget(CloseButton, 0);
 	_this->connect(CloseButton, SIGNAL(clicked()), SLOT(onCloseButtonClicked()));
 }
@@ -277,7 +291,10 @@ void CDockAreaTitleBar::onCloseButtonClicked()
 //============================================================================
 void CDockAreaTitleBar::onUndockButtonClicked()
 {
-	d->TabBar->makeAreaFloating(mapFromGlobal(QCursor::pos()), DraggingInactive);
+	if (d->DockArea->features().testFlag(CDockWidget::DockWidgetFloatable))
+	{
+		d->TabBar->makeAreaFloating(mapFromGlobal(QCursor::pos()), DraggingInactive);
+	}
 }
 
 
@@ -332,9 +349,10 @@ void CDockAreaTitleBar::setVisible(bool Visible)
 void CDockAreaTitleBar::showContextMenu(const QPoint& pos)
 {
 	QMenu Menu(this);
-	Menu.addAction(tr("Detach Area"), this, SLOT(onUndockButtonClicked()));
+	auto Action = Menu.addAction(tr("Detach Area"), this, SLOT(onUndockButtonClicked()));
+	Action->setEnabled(d->DockArea->features().testFlag(CDockWidget::DockWidgetFloatable));
 	Menu.addSeparator();
-	auto Action = Menu.addAction(tr("Close Area"), this, SLOT(onCloseButtonClicked()));
+	Action = Menu.addAction(tr("Close Area"), this, SLOT(onCloseButtonClicked()));
 	Action->setEnabled(d->DockArea->features().testFlag(CDockWidget::DockWidgetClosable));
 	Menu.addAction(tr("Close Other Areas"), d->DockArea, SLOT(closeOtherAreas()));
 	Menu.exec(mapToGlobal(pos));

src/DockAreaWidget.cpp

@@ -241,7 +241,7 @@ struct DockAreaWidgetPrivate
 	DockAreaLayout*		ContentsLayout	= nullptr;
 	CDockAreaTitleBar*	TitleBar		= nullptr;
 	CDockManager*		DockManager		= nullptr;
-	bool UpdateCloseButton = false;
+	bool UpdateTitleBarButtons = false;
 
 	/**
 	 * Private data constructor
@@ -295,9 +295,9 @@ struct DockAreaWidgetPrivate
 	}
 
 	/**
-	 * Udpates the enable state of the close button
+	 * Udpates the enable state of the close and detach button
 	 */
-	void updateCloseButtonState();
+	void updateTitleBarButtonStates();
 };
 // struct DockAreaWidgetPrivate
 
@@ -322,17 +322,19 @@ void DockAreaWidgetPrivate::createTitleBar()
 
 
 //============================================================================
-void DockAreaWidgetPrivate::updateCloseButtonState()
+void DockAreaWidgetPrivate::updateTitleBarButtonStates()
 {
 	if (_this->isHidden())
 	{
-		UpdateCloseButton = true;
+		UpdateTitleBarButtons = true;
 		return;
 	}
 
 	TitleBar->button(TitleBarButtonClose)->setEnabled(
 		_this->features().testFlag(CDockWidget::DockWidgetClosable));
-	UpdateCloseButton = false;
+	TitleBar->button(TitleBarButtonUndock)->setEnabled(
+		_this->features().testFlag(CDockWidget::DockWidgetFloatable));
+	UpdateTitleBarButtons = false;
 }
 
 
@@ -400,7 +402,7 @@ void CDockAreaWidget::insertDockWidget(int index, CDockWidget* DockWidget,
 		setCurrentIndex(index);
 	}
 	DockWidget->setDockArea(this);
-	d->updateCloseButtonState();
+	d->updateTitleBarButtonStates();
 }
 
 
@@ -414,14 +416,15 @@ void CDockAreaWidget::removeDockWidget(CDockWidget* DockWidget)
 	auto TabWidget = DockWidget->tabWidget();
 	TabWidget->hide();
 	d->tabBar()->removeTab(TabWidget);
+	CDockContainerWidget* DockContainer = dockContainer();
 	if (NextOpenDockWidget)
 	{
 		setCurrentDockWidget(NextOpenDockWidget);
 	}
-	else if (d->ContentsLayout->isEmpty())
+	else if (d->ContentsLayout->isEmpty() && DockContainer->dockAreaCount() > 1)
 	{
 		qDebug() << "Dock Area empty";
-		dockContainer()->removeDockArea(this);
+		DockContainer->removeDockArea(this);
 		this->deleteLater();
 	}
 	else
@@ -432,16 +435,15 @@ void CDockAreaWidget::removeDockWidget(CDockWidget* DockWidget)
 		hideAreaWithNoVisibleContent();
 	}
 
-	d->updateCloseButtonState();
+	d->updateTitleBarButtonStates();
 	updateTitleBarVisibility();
-	auto TopLevelDockWidget = dockContainer()->topLevelDockWidget();
+	auto TopLevelDockWidget = DockContainer->topLevelDockWidget();
 	if (TopLevelDockWidget)
 	{
 		TopLevelDockWidget->emitTopLevelChanged(true);
 	}
 
 #if (ADS_DEBUG_LEVEL > 0)
-	CDockContainerWidget* DockContainer = dockContainer();
 	DockContainer->dumpLayout();
 #endif
 }
@@ -765,9 +767,9 @@ void CDockAreaWidget::toggleView(bool Open)
 void CDockAreaWidget::setVisible(bool Visible)
 {
 	Super::setVisible(Visible);
-	if (d->UpdateCloseButton)
+	if (d->UpdateTitleBarButtons)
 	{
-		d->updateCloseButtonState();
+		d->updateTitleBarButtonStates();
 	}
 }
 

src/DockContainerWidget.cpp

@@ -998,6 +998,15 @@ CDockAreaWidget* CDockContainerWidget::addDockWidget(DockWidgetArea area, CDockW
 	}
 }
 
+//============================================================================
+void CDockContainerWidget::removeDockWidget(CDockWidget* Dockwidget)
+{
+	CDockAreaWidget* Area = Dockwidget->dockAreaWidget();
+	if (Area)
+	{
+		Area->removeDockWidget(Dockwidget);
+	}
+}
 
 //============================================================================
 unsigned int CDockContainerWidget::zOrderIndex() const
@@ -1057,6 +1066,12 @@ void CDockContainerWidget::removeDockArea(CDockAreaWidget* area)
 	area->setParent(nullptr);
 	internal::hideEmptyParentSplitters(Splitter);
 
+	// Remove this area from cached areas
+	const auto& cache = d->LastAddedAreaCache;
+	if (auto p = std::find(cache, cache+sizeof(cache)/sizeof(cache[0]), area)) {
+		d->LastAddedAreaCache[std::distance(cache, p)] = nullptr;
+	}
+
 	// If splitter has more than 1 widgets, we are finished and can leave
 	if (Splitter->count() >  1)
 	{
@@ -1274,6 +1289,7 @@ bool CDockContainerWidget::restoreState(QXmlStreamReader& s, bool Testing)
 	{
 		d->VisibleDockAreaCount = -1;// invalidate the dock area count
 		d->DockAreas.clear();
+		std::fill(std::begin(d->LastAddedAreaCache),std::end(d->LastAddedAreaCache), nullptr);
 	}
 
 	if (IsFloating)

src/DockContainerWidget.h

@@ -166,6 +166,11 @@ public:
 	CDockAreaWidget* addDockWidget(DockWidgetArea area, CDockWidget* Dockwidget,
 		CDockAreaWidget* DockAreaWidget = nullptr);
 
+	/**
+	 * Removes dockwidget
+	 */
+	void removeDockWidget(CDockWidget* Dockwidget);
+
 	/**
 	 * Returns the current zOrderIndex
 	 */

src/DockManager.cpp

@@ -145,7 +145,11 @@ DockManagerPrivate::DockManagerPrivate(CDockManager* _public) :
 void DockManagerPrivate::loadStylesheet()
 {
 	QString Result;
+#ifdef Q_OS_LINUX
+    QFile StyleSheetFile(":ads/stylesheets/default_linux.css");
+#else
 	QFile StyleSheetFile(":ads/stylesheets/default.css");
+#endif
 	StyleSheetFile.open(QIODevice::ReadOnly);
 	QTextStream StyleSheetStream(&StyleSheetFile);
 	Result = StyleSheetStream.readAll();
@@ -336,8 +340,9 @@ void DockManagerPrivate::emitTopLevelEvents()
 
 
 //============================================================================
-bool DockManagerPrivate::restoreState(const QByteArray &state, int version)
+bool DockManagerPrivate::restoreState(const QByteArray& State, int version)
 {
+	QByteArray state = State.startsWith("<?xml") ? State : qUncompress(State);
     if (!checkFormat(state, version))
     {
     	qDebug() << "checkFormat: Error checking format!!!!!!!";
@@ -489,11 +494,11 @@ unsigned int CDockManager::zOrderIndex() const
 
 
 //============================================================================
-QByteArray CDockManager::saveState(eXmlMode XmlMode, int version) const
+QByteArray CDockManager::saveState(int version) const
 {
     QByteArray xmldata;
     QXmlStreamWriter s(&xmldata);
-	s.setAutoFormatting(XmlAutoFormattingEnabled == XmlMode);
+	s.setAutoFormatting(d->ConfigFlags.testFlag(XmlAutoFormattingEnabled));
     s.writeStartDocument();
 		s.writeStartElement("QtAdvancedDockingSystem");
 		s.writeAttribute("Version", QString::number(version));
@@ -506,7 +511,7 @@ QByteArray CDockManager::saveState(eXmlMode XmlMode, int version) const
 		s.writeEndElement();
     s.writeEndDocument();
 
-    return xmldata;
+    return d->ConfigFlags.testFlag(XmlCompressionEnabled) ? qCompress(xmldata, 9) : xmldata;
 }
 
 
@@ -565,9 +570,13 @@ CDockAreaWidget* CDockManager::addDockWidgetTab(DockWidgetArea area,
 	{
 		return addDockWidget(ads::CenterDockWidgetArea, Dockwidget, AreaWidget);
 	}
+	else if (!openedDockAreas().isEmpty())
+	{
+		return addDockWidget(area, Dockwidget, openedDockAreas().last());
+	}
 	else
 	{
-		return addDockWidget(area, Dockwidget, AreaWidget);
+		return addDockWidget(area, Dockwidget, nullptr);
 	}
 }
 
@@ -586,6 +595,12 @@ CDockWidget* CDockManager::findDockWidget(const QString& ObjectName) const
 	return d->DockWidgetsMap.value(ObjectName, nullptr);
 }
 
+//============================================================================
+void CDockManager::removeDockWidget(CDockWidget* Dockwidget)
+{
+	d->DockWidgetsMap.remove(Dockwidget->objectName());
+	CDockContainerWidget::removeDockWidget(Dockwidget);
+}
 
 //============================================================================
 QMap<QString, CDockWidget*> CDockManager::dockWidgetsMap() const

src/DockManager.h

@@ -51,7 +51,9 @@ struct DockWidgetTabPrivate;
 struct DockAreaWidgetPrivate;
 
 /**
- * The central dock manager that maintains the complete docking system
+ * The central dock manager that maintains the complete docking system.
+ * With the configuration flags you can globally control the functionality
+ * of the docking system.
  **/
 class ADS_EXPORT CDockManager : public CDockContainerWidget
 {
@@ -108,12 +110,6 @@ public:
 		MenuAlphabeticallySorted
 	};
 
-	enum eXmlMode
-	{
-		XmlAutoFormattingDisabled,
-		XmlAutoFormattingEnabled
-	};
-
 	/**
 	 * These global configuration flags configure some global dock manager
 	 * settings.
@@ -124,7 +120,9 @@ public:
 		DockAreaHasCloseButton = 0x02,     //!< If the flag is set each dock area has a close button
 		DockAreaCloseButtonClosesTab = 0x04,//!< If the flag is set, the dock area close button closes the active tab, if not set, it closes the complete cock area
 		OpaqueSplitterResize = 0x08, //!< See QSplitter::setOpaqueResize() documentation
-		DefaultConfig = ActiveTabHasCloseButton | DockAreaHasCloseButton | OpaqueSplitterResize, ///< the default configuration
+		XmlAutoFormattingEnabled = 0x10,//!< If enabled, the XML writer automatically adds line-breaks and indentation to empty sections between elements (ignorable whitespace).
+		XmlCompressionEnabled = 0x20,//!< If enabled, the XML output will be compressed and is not human readable anymore
+		DefaultConfig = ActiveTabHasCloseButton | DockAreaHasCloseButton | OpaqueSplitterResize | XmlCompressionEnabled, ///< the default configuration
 	};
 	Q_DECLARE_FLAGS(ConfigFlags, eConfigFlag)
 
@@ -192,6 +190,11 @@ public:
 	 */
 	CDockWidget* findDockWidget(const QString& ObjectName) const;
 
+	/**
+	 * Remove the given Dock from the dock manager
+	 */
+	void removeDockWidget(CDockWidget* Dockwidget);
+
 	/**
 	 * This function returns a readable reference to the internal dock
 	 * widgets map so that it is possible to iterate over all dock widgets
@@ -223,7 +226,7 @@ public:
 	 * The XmlMode XmlAutoFormattingDisabled is better if you would like to have
 	 * a more compact XML output - i.e. for storage in ini files.
 	 */
-	QByteArray saveState(eXmlMode XmlMode = XmlAutoFormattingDisabled, int version = 0) const;
+	QByteArray saveState(int version = 0) const;
 
 	/**
 	 * Restores the state of this dockmanagers dockwidgets.

src/DockOverlay.cpp

@@ -132,6 +132,21 @@ struct DockOverlayCrossPrivate
 		return Color;
 	}
 
+    //============================================================================
+    /**
+     * Helper function that returns the drop indicator width depending on the
+     * operating system
+     */
+    qreal dropIndicatiorWidth(QLabel* l) const
+    {
+    #ifdef Q_OS_LINUX
+        Q_UNUSED(l)
+        return 40;
+    #else
+        return static_cast<qreal>(l->fontMetrics().height()) * 3.f;
+    #endif
+    }
+
 
 	//============================================================================
 	QWidget* createDropIndicatorWidget(DockWidgetArea DockWidgetArea,
@@ -140,7 +155,7 @@ struct DockOverlayCrossPrivate
 		QLabel* l = new QLabel();
 		l->setObjectName("DockWidgetAreaLabel");
 
-		const qreal metric = static_cast<qreal>(l->fontMetrics().height()) * 3.f;
+        const qreal metric = dropIndicatiorWidth(l);
 		const QSizeF size(metric, metric);
 
 		l->setPixmap(createHighDpiDropIndicatorPixmap(size, DockWidgetArea, Mode));
@@ -154,7 +169,7 @@ struct DockOverlayCrossPrivate
 	void updateDropIndicatorIcon(QWidget* DropIndicatorWidget)
 	{
 		QLabel* l = qobject_cast<QLabel*>(DropIndicatorWidget);
-		const qreal metric = static_cast<qreal>(l->fontMetrics().height()) * 3.f;
+        const qreal metric = dropIndicatiorWidth(l);
 		const QSizeF size(metric, metric);
 
 		int Area = l->property("dockWidgetArea").toInt();

src/DockWidget.cpp

@@ -243,21 +243,35 @@ void CDockWidget::setToggleViewActionChecked(bool Checked)
 void CDockWidget::setWidget(QWidget* widget, eInsertMode InsertMode)
 {
 	QScrollArea* ScrollAreaWidget = qobject_cast<QScrollArea*>(widget);
-	if (ScrollAreaWidget || ForceNoScrollArea != InsertMode)
+	if (ScrollAreaWidget || ForceNoScrollArea == InsertMode)
+	{
+		d->Layout->addWidget(widget);
+		if (ScrollAreaWidget && ScrollAreaWidget->viewport())
+		{
+			ScrollAreaWidget->viewport()->setProperty("dockWidgetContent", true);
+		}
+	}
+	else
 	{
 		d->setupScrollArea();
 		d->ScrollArea->setWidget(widget);
 	}
-	else
-	{
-		d->Layout->addWidget(widget);
-	}
 
 	d->Widget = widget;
 	d->Widget->setProperty("dockWidgetContent", true);
 }
 
 
+//============================================================================
+QWidget* CDockWidget::takeWidget()
+{
+	d->ScrollArea->takeWidget();
+	d->Layout->removeWidget(d->Widget);
+	d->Widget->setParent(nullptr);
+    return d->Widget;
+}
+
+
 //============================================================================
 QWidget* CDockWidget::widget() const
 {

src/DockWidget.h

@@ -141,7 +141,7 @@ public:
 	enum DockWidgetFeature
 	{
 		DockWidgetClosable = 0x01,
-		DockWidgetMovable = 0x02,
+		DockWidgetMovable = 0x02,///< this feature is not properly implemented yet and is ignored
 		DockWidgetFloatable = 0x04,
 		AllDockWidgetFeatures = DockWidgetClosable | DockWidgetMovable | DockWidgetFloatable,
 		NoDockWidgetFeatures = 0x00
@@ -238,6 +238,11 @@ public:
 	 */
 	void setWidget(QWidget* widget, eInsertMode InsertMode = AutoScrollArea);
 
+	/**
+	 * Remove the widget from the dock and give ownership back to the caller
+	 */
+	QWidget* takeWidget();
+
 	/**
 	 * Returns the widget for the dock widget. This function returns zero if
 	 * the widget has not been set.

src/DockWidgetTab.cpp

@@ -146,12 +146,13 @@ void DockWidgetTabPrivate::createLayout()
 	CloseButton = new tCloseButton();
 	CloseButton->setObjectName("tabCloseButton");
 	// The standard icons do does not look good on high DPI screens
-	QIcon CloseIcon =  _this->style()->standardIcon(QStyle::SP_TitleBarCloseButton);
+	QIcon CloseIcon;
 	QPixmap normalPixmap = _this->style()->standardPixmap(QStyle::SP_TitleBarCloseButton, 0, CloseButton);
-	QPixmap disabledPixmap = internal::createTransparentPixmap(normalPixmap, 0.25);
-	CloseIcon.addPixmap(disabledPixmap, QIcon::Disabled);
+	CloseIcon.addPixmap(normalPixmap, QIcon::Normal);
+	CloseIcon.addPixmap(internal::createTransparentPixmap(normalPixmap, 0.25), QIcon::Disabled);
 	CloseButton->setIcon(CloseIcon);
-	CloseButton->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
+
+    CloseButton->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
 	CloseButton->setVisible(false);
 	#ifndef QT_NO_TOOLTIP
 	CloseButton->setToolTip(QObject::tr("Close Tab"));
@@ -223,7 +224,7 @@ bool DockWidgetTabPrivate::startFloating(eDragState DraggingState)
 
     if (DraggingFloatingWidget == DraggingState)
     {
-    	FloatingWidget->startDragging(DragStartMousePosition, Size);
+        FloatingWidget->startDragging(DragStartMousePosition, Size, _this);
     	auto Overlay = DockWidget->dockManager()->containerOverlay();
     	Overlay->setAllowedAreas(OuterDockAreas);
     	this->FloatingWidget = FloatingWidget;
@@ -327,7 +328,7 @@ void CDockWidgetTab::mouseMoveEvent(QMouseEvent* ev)
 		}
 
     	// Floating is only allowed for widgets that are movable
-        if (d->DockWidget->features().testFlag(CDockWidget::DockWidgetMovable))
+        if (d->DockWidget->features().testFlag(CDockWidget::DockWidgetFloatable))
         {
             d->startFloating();
         }
@@ -351,9 +352,10 @@ void CDockWidgetTab::contextMenuEvent(QContextMenuEvent* ev)
 
 	d->DragStartMousePosition = ev->pos();
 	QMenu Menu(this);
-	Menu.addAction(tr("Detach"), this, SLOT(onDetachActionTriggered()));
+	auto Action = Menu.addAction(tr("Detach"), this, SLOT(onDetachActionTriggered()));
+	Action->setEnabled(d->DockWidget->features().testFlag(CDockWidget::DockWidgetFloatable));
 	Menu.addSeparator();
-	auto Action = Menu.addAction(tr("Close"), this, SIGNAL(closeRequested()));
+	Action = Menu.addAction(tr("Close"), this, SIGNAL(closeRequested()));
 	Action->setEnabled(isClosable());
 	Menu.addAction(tr("Close Others"), this, SIGNAL(closeOtherTabsRequested()));
 	Menu.exec(mapToGlobal(ev->pos()));
@@ -468,7 +470,8 @@ void CDockWidgetTab::mouseDoubleClickEvent(QMouseEvent *event)
 	// If this is the last dock area in a dock container it does not make
 	// sense to move it to a new floating widget and leave this one
 	// empty
-	if (!d->DockArea->dockContainer()->isFloating() || d->DockArea->dockWidgetsCount() > 1)
+	if ((!d->DockArea->dockContainer()->isFloating() || d->DockArea->dockWidgetsCount() > 1)
+		&& d->DockWidget->features().testFlag(CDockWidget::DockWidgetFloatable))
 	{
 		d->DragStartMousePosition = event->pos();
 		d->startFloating(DraggingInactive);
@@ -504,13 +507,15 @@ bool CDockWidgetTab::isClosable() const
 //===========================================================================
 void CDockWidgetTab::onDetachActionTriggered()
 {
+	if (!d->DockWidget->features().testFlag(CDockWidget::DockWidgetFloatable))
+	{
+		return;
+	}
 	d->DragStartMousePosition = mapFromGlobal(QCursor::pos());
 	d->startFloating(DraggingInactive);
 }
 
 
-
-
 //============================================================================
 bool CDockWidgetTab::event(QEvent *e)
 {

src/FloatingDockContainer.cpp

@@ -45,7 +45,11 @@
 #include "DockWidget.h"
 #include "DockOverlay.h"
 
-#include <iostream>
+#ifdef Q_OS_LINUX
+#include "linux/FloatingWidgetTitleBar.h"
+#include <xcb/xcb.h>
+#endif
+
 
 namespace ads
 {
@@ -63,6 +67,10 @@ struct FloatingDockContainerPrivate
 	QPoint DragStartMousePosition;
 	CDockContainerWidget* DropContainer = nullptr;
 	CDockAreaWidget* SingleDockArea = nullptr;
+#ifdef Q_OS_LINUX
+    QWidget* MouseEventHandler = nullptr;
+    CFloatingWidgetTitleBar* TitleBar = nullptr;
+#endif
 
 	/**
 	 * Private data constructor
@@ -84,6 +92,15 @@ struct FloatingDockContainerPrivate
 	{
 		DraggingState = StateId;
 	}
+
+    void setWindowTitle(const QString& Text)
+    {
+#ifdef Q_OS_LINUX
+        TitleBar->setTitle(Text);
+#else
+        _this->setWindowTitle(Text);
+#endif
+    }
 };
 // struct FloatingDockContainerPrivate
 
@@ -216,26 +233,38 @@ void FloatingDockContainerPrivate::updateDropOverlays(const QPoint& GlobalPos)
 
 //============================================================================
 CFloatingDockContainer::CFloatingDockContainer(CDockManager* DockManager) :
-	QWidget(DockManager, Qt::Window),
+    tFloatingWidgetBase(DockManager),
 	d(new FloatingDockContainerPrivate(this))
 {
-	setWindowFlags(Qt::Window | Qt::WindowMaximizeButtonHint | Qt::WindowCloseButtonHint);
-	d->DockManager = DockManager;
+    d->DockManager = DockManager;
+    d->DockContainer = new CDockContainerWidget(DockManager, this);
+    connect(d->DockContainer, SIGNAL(dockAreasAdded()), this, SLOT(onDockAreasAddedOrRemoved()));
+    connect(d->DockContainer, SIGNAL(dockAreasRemoved()), this, SLOT(onDockAreasAddedOrRemoved()));
+
+#ifdef Q_OS_LINUX
+    d->TitleBar = new CFloatingWidgetTitleBar(this);
+    setWindowFlags(windowFlags() | Qt::Tool);
+    QDockWidget::setWidget(d->DockContainer);
+    QDockWidget::setFloating(true);
+    QDockWidget::setFeatures(QDockWidget::AllDockWidgetFeatures);
+    setTitleBarWidget(d->TitleBar);
+    connect(d->TitleBar, SIGNAL(closeRequested()), SLOT(close()));
+#else
+    setWindowFlags(Qt::Window | Qt::WindowMaximizeButtonHint | Qt::WindowCloseButtonHint);
     QBoxLayout* l = new QBoxLayout(QBoxLayout::TopToBottom);
     l->setContentsMargins(0, 0, 0, 0);
     l->setSpacing(0);
     setLayout(l);
+    l->addWidget(d->DockContainer);
+#endif
 
-    d->DockContainer = new CDockContainerWidget(DockManager, this);
-    connect(d->DockContainer, SIGNAL(dockAreasAdded()), this, SLOT(onDockAreasAddedOrRemoved()));
-    connect(d->DockContainer, SIGNAL(dockAreasRemoved()), this, SLOT(onDockAreasAddedOrRemoved()));
-	l->addWidget(d->DockContainer);
 	DockManager->registerFloatingWidget(this);
 
+
 	// We install an event filter to detect mouse release events because we
 	// do not receive mouse release event if the floating widget is behind
 	// the drop overlay cross
-	qApp->installEventFilter(this);
+    qApp->installEventFilter(this);
 }
 
 
@@ -244,14 +273,20 @@ CFloatingDockContainer::CFloatingDockContainer(CDockAreaWidget* DockArea) :
 	CFloatingDockContainer(DockArea->dockManager())
 {
 	d->DockContainer->addDockArea(DockArea);
+#ifdef Q_OS_LINUX
+    d->TitleBar->enableCloseButton(isClosable());
+#endif
 }
 
 
 //============================================================================
 CFloatingDockContainer::CFloatingDockContainer(CDockWidget* DockWidget) :
-	CFloatingDockContainer(DockWidget->dockManager())
+    CFloatingDockContainer(DockWidget->dockManager())
 {
-	d->DockContainer->addDockWidget(CenterDockWidgetArea, DockWidget);
+    d->DockContainer->addDockWidget(CenterDockWidgetArea, DockWidget);
+#ifdef Q_OS_LINUX
+    d->TitleBar->enableCloseButton(isClosable());
+#endif
 }
 
 //============================================================================
@@ -290,7 +325,7 @@ void CFloatingDockContainer::changeEvent(QEvent *event)
 void CFloatingDockContainer::moveEvent(QMoveEvent *event)
 {
 	QWidget::moveEvent(event);
-	switch (d->DraggingState)
+    switch (d->DraggingState)
 	{
 	case DraggingMousePressed:
 		 d->setState(DraggingFloatingWidget);
@@ -302,7 +337,7 @@ void CFloatingDockContainer::moveEvent(QMoveEvent *event)
 		 break;
 	default:
 		break;
-	}
+    }
 }
 
 
@@ -320,11 +355,18 @@ void CFloatingDockContainer::closeEvent(QCloseEvent *event)
         // https://bugreports.qt.io/browse/QTBUG-73295
         // The following code is a workaround for Qt versions > 5.9.2 that seems
         // to work
-#if (QT_VERSION > 0x050902)
+    	// Starting from Qt version 5.12.2 this seems to work again. But
+    	// now the QEvent::NonClientAreaMouseButtonPress function returns always
+    	// Qt::RightButton even if the left button was pressed
+#ifndef Q_OS_LINUX
+#if (QT_VERSION > QT_VERSION_CHECK(5, 9, 2) && QT_VERSION < QT_VERSION_CHECK(5, 12, 2))
         event->ignore();
         this->hide();
 #else
         Super::closeEvent(event);
+#endif
+#else // Q_OS_LINUX
+        Super::closeEvent(event);
 #endif
     }
     else
@@ -352,13 +394,6 @@ void CFloatingDockContainer::hideEvent(QHideEvent *event)
 void CFloatingDockContainer::showEvent(QShowEvent *event)
 {
 	Super::showEvent(event);
-	/*for (auto DockArea : d->DockContainer->openedDockAreas())
-	{
-		for (auto DockWidget : DockArea->openedDockWidgets())
-		{
-			DockWidget->setToggleViewActionChecked(true);
-		}
-	}*/
 }
 
 
@@ -368,11 +403,28 @@ bool CFloatingDockContainer::event(QEvent *e)
 	switch (d->DraggingState)
 	{
 	case DraggingInactive:
-		if (e->type() == QEvent::NonClientAreaMouseButtonPress && QGuiApplication::mouseButtons() == Qt::LeftButton)
+	{
+		// Normally we would check here, if the left mouse button is pressed.
+		// But from QT version 5.12.2 on the mouse events from
+		// QEvent::NonClientAreaMouseButtonPress return the wrong mouse button
+		// The event always returns Qt::RightButton even if the left button
+		// is clicked.
+		// It is really great to work around the whole NonClientMouseArea
+		// bugs
+#if (QT_VERSION >= QT_VERSION_CHECK(5, 12, 2))
+		if (e->type() == QEvent::NonClientAreaMouseButtonPress /*&& QGuiApplication::mouseButtons().testFlag(Qt::LeftButton)*/)
 		{
 			qDebug() << "FloatingWidget::event Event::NonClientAreaMouseButtonPress" << e->type();
 			d->setState(DraggingMousePressed);
 		}
+#else
+		if (e->type() == QEvent::NonClientAreaMouseButtonPress && QGuiApplication::mouseButtons().testFlag(Qt::LeftButton))
+		{
+			qDebug() << "FloatingWidget::event Event::NonClientAreaMouseButtonPress" << e->type();
+			d->setState(DraggingMousePressed);
+		}
+#endif
+	}
 	break;
 
 	case DraggingMousePressed:
@@ -425,12 +477,13 @@ bool CFloatingDockContainer::event(QEvent *e)
 //============================================================================
 bool CFloatingDockContainer::eventFilter(QObject *watched, QEvent *event)
 {
-	Q_UNUSED(watched);
-	if (event->type() == QEvent::MouseButtonRelease && d->isState(DraggingFloatingWidget))
+    Q_UNUSED(watched);
+    if (event->type() == QEvent::MouseButtonRelease && d->isState(DraggingFloatingWidget))
 	{
 		qDebug() << "FloatingWidget::eventFilter QEvent::MouseButtonRelease";
+        finishDragging();
 		d->titleMouseReleaseEvent();
-	}
+    }
 
 	return false;
 }
@@ -438,11 +491,26 @@ bool CFloatingDockContainer::eventFilter(QObject *watched, QEvent *event)
 
 //============================================================================
 void CFloatingDockContainer::startFloating(const QPoint& DragStartMousePos, const QSize& Size,
-	eDragState DragState)
+    eDragState DragState, QWidget* MouseEventHandler)
 {
+#ifndef Q_OS_LINUX
+	Q_UNUSED(MouseEventHandler)
+#endif
 	resize(Size);
 	d->setState(DragState);
 	d->DragStartMousePosition = DragStartMousePos;
+#ifdef Q_OS_LINUX
+   if (DraggingFloatingWidget == DragState)
+   {
+       setAttribute(Qt::WA_X11NetWmWindowTypeDock, true);
+       setWindowOpacity(0.6);
+       d->MouseEventHandler = MouseEventHandler;
+       if (d->MouseEventHandler)
+       {
+           d->MouseEventHandler->grabMouse();
+       }
+   }
+#endif
 	moveFloating();
     show();
 
@@ -454,7 +522,7 @@ void CFloatingDockContainer::moveFloating()
 {
 	int BorderSize = (frameSize().width() - size().width()) / 2;
 	const QPoint moveToPos = QCursor::pos() - d->DragStartMousePosition - QPoint(BorderSize, 0);
-	move(moveToPos);
+    move(moveToPos);
 }
 
 
@@ -473,7 +541,7 @@ void CFloatingDockContainer::onDockAreasAddedOrRemoved()
 	if (TopLevelDockArea)
 	{
 		d->SingleDockArea = TopLevelDockArea;
-		this->setWindowTitle(d->SingleDockArea->currentDockWidget()->windowTitle());
+        d->setWindowTitle(d->SingleDockArea->currentDockWidget()->windowTitle());
 		connect(d->SingleDockArea, SIGNAL(currentChanged(int)), this,
 			SLOT(onDockAreaCurrentChanged(int)));
 	}
@@ -485,7 +553,7 @@ void CFloatingDockContainer::onDockAreasAddedOrRemoved()
 				SLOT(onDockAreaCurrentChanged(int)));
 			d->SingleDockArea = nullptr;
 		}
-		this->setWindowTitle(qApp->applicationDisplayName());
+        d->setWindowTitle(qApp->applicationDisplayName());
 	}
 }
 
@@ -496,11 +564,11 @@ void CFloatingDockContainer::updateWindowTitle()
 	auto TopLevelDockArea = d->DockContainer->topLevelDockArea();
 	if (TopLevelDockArea)
 	{
-		this->setWindowTitle(TopLevelDockArea->currentDockWidget()->windowTitle());
+        d->setWindowTitle(TopLevelDockArea->currentDockWidget()->windowTitle());
 	}
 	else
 	{
-		this->setWindowTitle(qApp->applicationDisplayName());
+        d->setWindowTitle(qApp->applicationDisplayName());
 	}
 }
 
@@ -509,7 +577,7 @@ void CFloatingDockContainer::updateWindowTitle()
 void CFloatingDockContainer::onDockAreaCurrentChanged(int Index)
 {
 	Q_UNUSED(Index);
-	this->setWindowTitle(d->SingleDockArea->currentDockWidget()->windowTitle());
+    d->setWindowTitle(d->SingleDockArea->currentDockWidget()->windowTitle());
 }
 
 
@@ -547,6 +615,24 @@ QList<CDockWidget*> CFloatingDockContainer::dockWidgets() const
 }
 
 
+
+//============================================================================
+void CFloatingDockContainer::finishDragging()
+{
+    qDebug() << "CFloatingDockContainer::finishDragging";
+#ifdef Q_OS_LINUX
+   setAttribute(Qt::WA_X11NetWmWindowTypeDock, false);
+   setWindowOpacity(1);
+   activateWindow();
+   if (d->MouseEventHandler)
+   {
+       d->MouseEventHandler->releaseMouse();
+       d->MouseEventHandler = nullptr;
+   }
+#endif
+}
+
+
 } // namespace ads
 
 //---------------------------------------------------------------------------

src/FloatingDockContainer.h

@@ -29,10 +29,16 @@
 //============================================================================
 //                                   INCLUDES
 //============================================================================
-#include <QWidget>
-
 #include "ads_globals.h"
 
+#ifdef Q_OS_LINUX
+#include <QDockWidget>
+#define tFloatingWidgetBase QDockWidget
+#else
+#include <QWidget>
+#define tFloatingWidgetBase QWidget
+#endif
+
 class QXmlStreamReader;
 
 namespace ads
@@ -49,13 +55,14 @@ class CDockWidgetTab;
 struct DockWidgetTabPrivate;
 class CDockAreaTitleBar;
 struct DockAreaTitleBarPrivate;
+class CFloatingWidgetTitleBar;
 
 /**
  * This implements a floating widget that is a dock container that accepts
  * docking of dock widgets like the main window and that can be docked into
  * another dock container
  */
-class ADS_EXPORT CFloatingDockContainer : public QWidget
+class ADS_EXPORT CFloatingDockContainer : public tFloatingWidgetBase
 {
 	Q_OBJECT
 private:
@@ -70,6 +77,7 @@ private:
 	friend struct DockAreaTitleBarPrivate;
 	friend class CDockWidget;
 	friend class CDockAreaWidget;
+    friend class CFloatingWidgetTitleBar;
 
 private slots:
 	void onDockAreasAddedOrRemoved();
@@ -82,23 +90,30 @@ protected:
 	 * depending on the start position given in Pos parameter
 	 */
 	void startFloating(const QPoint& DragStartMousePos, const QSize& Size,
-		eDragState DragState);
+        eDragState DragState, QWidget* MouseEventHandler);
 
 	/**
 	 * Call this function to start dragging the floating widget
 	 */
-	void startDragging(const QPoint& DragStartMousePos, const QSize& Size)
+    void startDragging(const QPoint& DragStartMousePos, const QSize& Size,
+        QWidget* MouseEventHandler)
 	{
-		startFloating(DragStartMousePos, Size, DraggingFloatingWidget);
+        startFloating(DragStartMousePos, Size, DraggingFloatingWidget, MouseEventHandler);
 	}
 
+	/**
+	 * Call this function if you explecitely want to signal that dragging has
+	 * finished
+	 */
+	void finishDragging();
+
 	/**
 	 * Call this function if you just want to initialize the position
 	 * and size of the floating widget
 	 */
 	void initFloatingGeometry(const QPoint& DragStartMousePos, const QSize& Size)
 	{
-		startFloating(DragStartMousePos, Size, DraggingInactive);
+        startFloating(DragStartMousePos, Size, DraggingInactive, nullptr);
 	}
 
 	/**

src/ads.qrc

@@ -3,5 +3,6 @@
         <file>stylesheets/default.css</file>
         <file>images/close-button.svg</file>
         <file>images/close-button-disabled.svg</file>
+        <file>stylesheets/default_linux.css</file>
     </qresource>
 </RCC>

src/linux/FloatingWidgetTitleBar.cpp

@@ -0,0 +1,187 @@
+/*******************************************************************************
+** Qt Advanced Docking System
+** Copyright (C) 2017 Uwe Kindler
+**
+** This library is free software; you can redistribute it and/or
+** modify it under the terms of the GNU Lesser General Public
+** License as published by the Free Software Foundation; either
+** version 2.1 of the License, or (at your option) any later version.
+**
+** This library is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+** Lesser General Public License for more details.
+**
+** You should have received a copy of the GNU Lesser General Public
+** License along with this library; If not, see <http://www.gnu.org/licenses/>.
+******************************************************************************/
+
+
+//============================================================================
+/// \file   FloatingWidgetTitleBar.cpp
+/// \author Uwe Kindler
+/// \date   13.05.2019
+/// \brief  Implementation of CFloatingWidgetTitleBar class
+//============================================================================
+
+//============================================================================
+//                                   INCLUDES
+//============================================================================
+#include "FloatingWidgetTitleBar.h"
+
+#include <iostream>
+
+#include <QHBoxLayout>
+#include <QPushButton>
+#include <QToolButton>
+#include <QPixmap>
+#include <QStyle>
+#include <QMouseEvent>
+
+#include "ads_globals.h"
+#include "ElidingLabel.h"
+#include "FloatingDockContainer.h"
+
+namespace ads
+{
+
+using tTabLabel = CElidingLabel;
+using tCloseButton = QPushButton;
+
+
+/**
+ * @brief Private data class of public interface CFloatingWidgetTitleBar
+ */
+struct FloatingWidgetTitleBarPrivate
+{
+    CFloatingWidgetTitleBar* _this; ///< public interface class
+    QLabel* IconLabel = nullptr;
+    tTabLabel* TitleLabel;
+    tCloseButton* CloseButton = nullptr;
+    CFloatingDockContainer* FloatingWidget = nullptr;
+    eDragState DragState = DraggingInactive;
+
+    FloatingWidgetTitleBarPrivate(CFloatingWidgetTitleBar* _public) : _this(_public) {}
+
+    /**
+     * Creates the complete layout including all controls
+     */
+    void createLayout();
+};
+
+
+//============================================================================
+void FloatingWidgetTitleBarPrivate::createLayout()
+{
+    TitleLabel = new tTabLabel();
+    TitleLabel->setElideMode(Qt::ElideRight);
+    TitleLabel->setText("DockWidget->windowTitle()");
+    TitleLabel->setObjectName("floatingTitleLabel");
+    TitleLabel->setAlignment(Qt::AlignLeft);
+
+    CloseButton = new tCloseButton();
+    CloseButton->setObjectName("floatingTitleCloseButton");
+    CloseButton->setFlat(true);
+    //CloseButton->setAutoRaise(true);
+    // The standard icons do does not look good on high DPI screens
+    QIcon CloseIcon;
+    QPixmap normalPixmap = _this->style()->standardPixmap(QStyle::SP_TitleBarCloseButton, 0, CloseButton);
+    CloseIcon.addPixmap(normalPixmap, QIcon::Normal);
+    CloseIcon.addPixmap(internal::createTransparentPixmap(normalPixmap, 0.25), QIcon::Disabled);
+    CloseButton->setIcon(_this->style()->standardIcon(QStyle::SP_TitleBarCloseButton));
+    CloseButton->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
+    CloseButton->setVisible(true);
+    CloseButton->setFocusPolicy(Qt::NoFocus);
+    _this->connect(CloseButton, SIGNAL(clicked()), SIGNAL(closeRequested()));
+
+    QFontMetrics fm(TitleLabel->font());
+    int Spacing = qRound(fm.height() / 4.0);
+
+    // Fill the layout
+    QBoxLayout* Layout = new QBoxLayout(QBoxLayout::LeftToRight);
+    Layout->setContentsMargins(6,0,0,0);
+    Layout->setSpacing(0);
+    _this->setLayout(Layout);
+    Layout->addWidget(TitleLabel, 1);
+    Layout->addSpacing(Spacing);
+    Layout->addWidget(CloseButton);
+    Layout->setAlignment(Qt::AlignCenter);
+
+    TitleLabel->setVisible(true);
+}
+
+
+//============================================================================
+CFloatingWidgetTitleBar::CFloatingWidgetTitleBar(CFloatingDockContainer *parent)
+    : QWidget(parent),
+      d(new FloatingWidgetTitleBarPrivate(this))
+{
+    d->FloatingWidget = parent;
+    d->createLayout();
+}
+
+
+//============================================================================
+CFloatingWidgetTitleBar::~CFloatingWidgetTitleBar()
+{
+    delete d;
+}
+
+
+//============================================================================
+void CFloatingWidgetTitleBar::mousePressEvent(QMouseEvent* ev)
+{
+    if (ev->button() == Qt::LeftButton)
+    {
+        d->DragState = DraggingFloatingWidget;
+        d->FloatingWidget->startDragging(ev->pos(), d->FloatingWidget->size(), this);
+        return;
+    }
+    Super::mousePressEvent(ev);
+}
+
+
+//============================================================================
+void CFloatingWidgetTitleBar::mouseReleaseEvent(QMouseEvent* ev)
+{
+    d->DragState = DraggingInactive;
+    Super::mouseReleaseEvent(ev);
+}
+
+
+//============================================================================
+void CFloatingWidgetTitleBar::mouseMoveEvent(QMouseEvent* ev)
+{
+    if (!(ev->buttons() & Qt::LeftButton) || DraggingInactive == d->DragState)
+    {
+        d->DragState = DraggingInactive;
+        Super::mouseMoveEvent(ev);
+        return;
+    }
+
+    // move floating window
+    if (DraggingFloatingWidget == d->DragState)
+    {
+        d->FloatingWidget->moveFloating();
+        Super::mouseMoveEvent(ev);
+        return;
+    }
+    Super::mouseMoveEvent(ev);
+}
+
+
+//============================================================================
+void CFloatingWidgetTitleBar::enableCloseButton(bool Enable)
+{
+    d->CloseButton->setEnabled(Enable);
+}
+
+
+//============================================================================
+void CFloatingWidgetTitleBar::setTitle(const QString& Text)
+{
+    d->TitleLabel->setText(Text);
+}
+
+
+} // namespace ads

src/linux/FloatingWidgetTitleBar.h

@@ -0,0 +1,68 @@
+#ifndef FLOATINGWIDGETTITLEBAR_H
+#define FLOATINGWIDGETTITLEBAR_H
+/*******************************************************************************
+** Qt Advanced Docking System
+** Copyright (C) 2017 Uwe Kindler
+**
+** This library is free software; you can redistribute it and/or
+** modify it under the terms of the GNU Lesser General Public
+** License as published by the Free Software Foundation; either
+** version 2.1 of the License, or (at your option) any later version.
+**
+** This library is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+** Lesser General Public License for more details.
+**
+** You should have received a copy of the GNU Lesser General Public
+** License along with this library; If not, see <http://www.gnu.org/licenses/>.
+******************************************************************************/
+
+
+//============================================================================
+/// \file   FloatingWidgetTitleBar.h
+/// \author Uwe Kindler
+/// \date   13.05.2019
+/// \brief  Declaration of CFloatingWidgetTitleBar class
+//============================================================================
+
+//============================================================================
+//                                   INCLUDES
+//============================================================================
+#include <QWidget>
+
+namespace ads
+{
+class CFloatingDockContainer;
+
+struct FloatingWidgetTitleBarPrivate;
+
+class CFloatingWidgetTitleBar : public QWidget
+{
+    Q_OBJECT
+private:
+   FloatingWidgetTitleBarPrivate* d; ///< private data (pimpl)
+
+protected:
+    virtual void mousePressEvent(QMouseEvent* ev) override;
+    virtual void mouseReleaseEvent(QMouseEvent* ev) override;
+    virtual void mouseMoveEvent(QMouseEvent* ev) override;
+
+public:
+   using Super = QWidget;
+    explicit CFloatingWidgetTitleBar (CFloatingDockContainer *parent = nullptr);
+
+   /**
+    * Virtual Destructor
+    */
+   virtual ~CFloatingWidgetTitleBar();
+
+   void enableCloseButton(bool Enable);
+
+   void setTitle(const QString& Text);
+
+signals:
+   void closeRequested();
+};
+} // namespace ads
+#endif // FLOATINGWIDGETTITLEBAR_H

src/src.pro

@@ -41,9 +41,8 @@ HEADERS += \
     DockSplitter.h \
     DockAreaTitleBar.h \
     ElidingLabel.h
-    
-    
-    
+
+
 SOURCES += \
     ads_globals.cpp \
     DockAreaWidget.cpp \
@@ -58,6 +57,12 @@ SOURCES += \
     DockAreaTitleBar.cpp \
     ElidingLabel.cpp
 
+
+unix {
+HEADERS += linux/FloatingWidgetTitleBar.h
+SOURCES += linux/FloatingWidgetTitleBar.cpp
+}
+
 isEmpty(PREFIX){
 	PREFIX=..\installed
 	warning("Install Prefix not set")
@@ -66,3 +71,5 @@ headers.path=$$PREFIX/include
 headers.files=$$HEADERS
 target.path=$$PREFIX/lib
 INSTALLS += headers target
+
+DISTFILES +=

src/stylesheets/default.css

@@ -63,7 +63,7 @@ ads--CDockWidget
 #closeButton,
 #undockButton
 {
-	padding: 0 -2px;
+	padding: 0px -2px;
 }
 
 

src/stylesheets/default_linux.css

@@ -0,0 +1,96 @@
+
+/*
+ * Default style sheet on Windows Platforms
+ * Note: Always use CSS-classes with and without "ads--" namespace to support Qt4 & Qt5
+ */
+
+ads--CDockContainerWidget
+{
+    background: palette(dark);
+}
+
+ads--CDockContainerWidget QSplitter::handle
+{
+    background: palette(dark);
+}
+
+ads--CDockAreaWidget
+{
+    background: palette(window);
+    border: 1px solid white;
+}
+
+ads--CDockAreaWidget #tabsMenuButton::menu-indicator
+{
+    image: none;
+}
+
+
+ads--CDockWidgetTab
+{
+    background: palette(window);
+    border-color: palette(light);
+    border-style: solid;
+    border-width: 0 1px 0 0;
+    padding: 0 0px;
+}
+
+ads--CDockWidgetTab[activeTab="true"]
+{
+    background: qlineargradient(spread:pad, x1:0, y1:0, x2:0, y2:0.5, stop:0 palette(window), stop:1 palette(light));
+    /*background: palette(highlight);*/
+}
+
+ads--CDockWidgetTab QLabel
+{
+    color: palette(dark);
+}
+
+ads--CDockWidgetTab[activeTab="true"] QLabel
+{
+    color: palette(foreground);
+}
+
+ads--CDockWidget
+{
+    background: palette(light);
+    border-color: palette(light);
+    border-style: solid;
+    border-width: 1px 0 0 0;
+}
+
+#tabsMenuButton,
+#closeButton,
+#undockButton
+{
+	padding: 0px -2px;
+}
+
+
+QScrollArea#dockWidgetScrollArea
+{
+	padding: 0px;
+	border: none;
+}
+
+
+#tabCloseButton
+{
+        margin-top: 2px;
+        background: none;
+        border: none;
+        padding: 0px -2px;
+}
+
+#tabCloseButton:hover
+{
+        border: 1px solid rgba(0, 0, 0, 32);
+        background: rgba(0, 0, 0, 16);
+}
+
+#tabCloseButton:pressed
+{
+        background: rgba(0, 0, 0, 32);
+}
+
+