Detachable windows (#3532)

Allows detaching a window from LMMS's main window, making things like working on multiple screens easier.

The behavior of detached windows can be customized in the Settings.

Closes #1259

---------

Signed-off-by: Dalton Messmer <messmer.dalton@gmail.com>
Co-authored-by: Hyunjin Song <tteu.ingog@gmail.com>
Co-authored-by: Dalton Messmer <messmer.dalton@gmail.com>
Co-authored-by: SpomJ <mihail_a_m@mail.ru>

data/themes/default/detach.svg

@@ -0,0 +1,6 @@
+<svg width="17" height="17" version="1.1" viewBox="0 0 17 17" xmlns="http://www.w3.org/2000/svg">
+	<g fill="#fff">
+		<rect x="4" y="11" width="9" height="2"/>
+		<path d="m4 9 4.5-5 4.5 5"/>
+	</g>
+</svg>

include/ControllerDialog.h

@@ -40,22 +40,10 @@ namespace gui
 
 class ControllerDialog : public QWidget, public ModelView
 {
-    Q_OBJECT
 public:
-	ControllerDialog( Controller * _controller, QWidget * _parent );
-
+	ControllerDialog(Controller* controller, QWidget* parent);
 	~ControllerDialog() override = default;
-
-
-signals:
-	void closed();
-
-
-protected:
-	void closeEvent( QCloseEvent * _ce ) override;
-
-} ;
-
+};
 
 } // namespace gui
 

include/ControllerRackView.h

@@ -29,7 +29,6 @@
 
 #include "SerializingObject.h"
 
-
 class QPushButton;
 class QScrollArea;
 class QVBoxLayout;
@@ -45,7 +44,6 @@ namespace gui
 
 class ControllerView;
 
-
 class ControllerRackView : public QWidget, public SerializingObject
 {
 	Q_OBJECT
@@ -69,9 +67,6 @@ public slots:
 	void addController(Controller* controller);
 	void removeController(Controller* controller);
 
-protected:
-	void closeEvent( QCloseEvent * _ce ) override;
-
 private slots:
 	void addController();
 

include/ControllerView.h

@@ -64,7 +64,6 @@ public:
 public slots:
 	void editControls();
 	void removeController();
-	void closeControls();
 	void renameController();
 	void moveUp();
 	void moveDown();
@@ -85,9 +84,7 @@ private:
 	QMdiSubWindow * m_subWindow;
 	ControllerDialog * m_controllerDlg;
 	QLabel * m_nameLabel;
-	bool m_show;
-
-} ;
+};
 
 
 } // namespace lmms::gui

include/Editor.h

@@ -57,8 +57,8 @@ protected:
 	DropToolBar * addDropToolBar(Qt::ToolBarArea whereToAdd, QString const & windowTitle);
 	DropToolBar * addDropToolBar(QWidget * parent, Qt::ToolBarArea whereToAdd, QString const & windowTitle);
 
-	void closeEvent(QCloseEvent * event) override;
-	void keyPressEvent(QKeyEvent *ke) override;
+	void keyPressEvent(QKeyEvent* ke) override;
+
 public slots:
 	//! Called by pressing the space key. Plays or stops.
 	void togglePlayStop();

include/EffectControlDialog.h

@@ -35,30 +35,18 @@ namespace lmms
 
 class EffectControls;
 
-
 namespace gui
 {
 
 class LMMS_EXPORT EffectControlDialog : public QWidget, public ModelView
 {
-	Q_OBJECT
 public:
-	EffectControlDialog( EffectControls * _controls );
+	EffectControlDialog(EffectControls* controls);
 	~EffectControlDialog() override = default;
 
-	virtual bool isResizable() const {return false;}
-
-
-signals:
-	void closed();
-
-
 protected:
-	void closeEvent( QCloseEvent * _ce ) override;
-
-	EffectControls * m_effectControls;
-
-} ;
+	EffectControls* m_effectControls;
+};
 
 } // namespace gui
 

include/EffectView.h

@@ -73,8 +73,6 @@ public slots:
 	void moveUp();
 	void moveDown();
 	void deletePlugin();
-	void closeEffects();
-
 
 signals:
 	void movedUp(EffectView* view);

include/MainWindow.h

@@ -141,9 +141,13 @@ public:
 
 	static void saveWidgetState( QWidget * _w, QDomElement & _de );
 	static void restoreWidgetState( QWidget * _w, const QDomElement & _de );
+	void setAllSubWindowsDetached(bool detached);
 
 	bool eventFilter(QObject* watched, QEvent* event) override;
 
+signals:
+	void detachAllSubWindows(bool detached);
+
 public slots:
 	void resetWindowTitle();
 

include/MicrotunerConfig.h

@@ -59,9 +59,6 @@ public slots:
 	void updateScaleForm();
 	void updateKeymapForm();
 
-protected:
-	void closeEvent(QCloseEvent *ce) override;
-
 private slots:
 	bool loadScaleFromFile();
 	bool loadKeymapFromFile();

include/MixerView.h

@@ -44,8 +44,11 @@ namespace lmms
 
 namespace lmms::gui
 {
-class LMMS_EXPORT MixerView : public QWidget, public ModelView,
-					public SerializingObjectHook
+
+class LMMS_EXPORT MixerView
+	: public QWidget
+	, public ModelView
+	, public SerializingObjectHook
 {
 	Q_OBJECT
 public:
@@ -94,9 +97,6 @@ public:
 public slots:
 	int addNewChannel();
 
-protected:
-	void closeEvent(QCloseEvent* ce) override;
-
 private slots:
 	void updateFaders();
 	// TODO This should be improved. Currently the solo and mute models are connected via

include/ProjectNotes.h

@@ -58,7 +58,6 @@ public:
 
 
 protected:
-	void closeEvent( QCloseEvent * _ce ) override;
 	void setupActions();
 
 

include/SampleTrackWindow.h

@@ -47,7 +47,7 @@ class SampleTrackWindow : public QWidget, public ModelView, public SerializingOb
 {
 	Q_OBJECT
 public:
-	SampleTrackWindow(SampleTrackView * tv);
+	SampleTrackWindow(SampleTrackView* stv);
 	~SampleTrackWindow() override = default;
 
 	SampleTrack * model()
@@ -76,7 +76,7 @@ public slots:
 
 protected:
 	// capture close-events for toggling sample-track-button
-	void closeEvent(QCloseEvent * ce) override;
+	void closeEvent(QCloseEvent* ce) override;
 
 	void saveSettings(QDomDocument & doc, QDomElement & element) override;
 	void loadSettings(const QDomElement & element) override;

include/SetupDialog.h

@@ -85,6 +85,7 @@ private slots:
 	void toggleMMPZ(bool enabled);
 	void toggleDisableBackup(bool enabled);
 	void toggleOpenLastProject(bool enabled);
+	void detachBehaviorChanged();
 	void loopMarkerModeChanged();
 	void setLanguage(int lang);
 
@@ -147,6 +148,8 @@ private:
 	bool m_MMPZ;
 	bool m_disableBackup;
 	bool m_openLastProject;
+	QString m_detachBehavior;
+	QComboBox* m_detachBehaviorComboBox;
 	QString m_loopMarkerMode;
 	QComboBox* m_loopMarkerComboBox;
 	QString m_autoScroll;

include/SongEditor.h

@@ -94,7 +94,6 @@ public slots:
 	void selectAllClips( bool select );
 
 protected:
-	void closeEvent( QCloseEvent * ce ) override;
 	void mousePressEvent(QMouseEvent * me) override;
 	void mouseMoveEvent(QMouseEvent * me) override;
 	void mouseReleaseEvent(QMouseEvent * me) override;

include/SubWindow.h

@@ -63,24 +63,34 @@ public:
 	QBrush activeColor() const;
 	QColor textShadowColor() const;
 	QColor borderColor() const;
+	QMargins decorationMargins() const;
 	void setActiveColor( const QBrush & b );
 	void setTextShadowColor( const QColor &c );
 	void setBorderColor( const QColor &c );
 	int titleBarHeight() const;
 	int frameWidth() const;
+	bool isDetachable() const;
+	void setDetachable(bool on);
+	bool isDetached() const;
+	void setDetached(bool on);
 
 	// TODO Needed to update the title bar when replacing instruments.
 	// Update works automatically if QMdiSubWindows are used.
 	void updateTitleBar();
 
+public slots:
+	void detach();
+	void attach();
+	void setVisible(bool visible) override;
+
 protected:
 	// hook the QWidget move/resize events to update the tracked geometry
-	void moveEvent( QMoveEvent * event ) override;
-	void resizeEvent( QResizeEvent * event ) override;
-	void paintEvent( QPaintEvent * pe ) override;
-	void changeEvent( QEvent * event ) override;
-
-	QPushButton* addTitleButton(const std::string& iconName, const QString& toolTip);
+	void moveEvent(QMoveEvent* event) override;
+	void resizeEvent(QResizeEvent* event) override;
+	void paintEvent(QPaintEvent* pe) override;
+	void changeEvent(QEvent* event) override;
+	void showEvent(QShowEvent* e) override;
+	bool eventFilter(QObject* obj, QEvent* event) override;
 
 signals:
 	void focusLost();
@@ -91,6 +101,7 @@ private:
 	QPushButton * m_closeBtn;
 	QPushButton * m_maximizeBtn;
 	QPushButton * m_restoreBtn;
+	QPushButton* m_detachBtn;
 	QBrush m_activeColor;
 	QColor m_textShadowColor;
 	QColor m_borderColor;
@@ -99,6 +110,7 @@ private:
 	QLabel * m_windowTitle;
 	QGraphicsDropShadowEffect * m_shadow;
 	bool m_hasFocus;
+	bool m_isDetachable;
 
 	static void elideText( QLabel *label, QString text );
 	void adjustTitleBar();

plugins/Amplifier/AmplifierControlDialog.cpp

@@ -57,6 +57,7 @@ AmplifierControlDialog::AmplifierControlDialog(AmplifierControls* controls) :
 	gridLayout->addWidget(makeKnob(tr("PAN"), tr("Panning:"), "%", &controls->m_panModel, false), 0, 1, Qt::AlignHCenter);
 	gridLayout->addWidget(makeKnob(tr("LEFT"), tr("Left gain:"), "%", &controls->m_leftModel, true), 1, 0, Qt::AlignHCenter);
 	gridLayout->addWidget(makeKnob(tr("RIGHT"), tr("Right gain:"), "%", &controls->m_rightModel, true), 1, 1, Qt::AlignHCenter);
+	gridLayout->setSizeConstraint(QLayout::SetFixedSize);
 }
 
 } // namespace lmms::gui

plugins/BassBooster/BassBoosterControlDialog.cpp

@@ -67,6 +67,7 @@ BassBoosterControlDialog::BassBoosterControlDialog( BassBoosterControls* control
 
 	tl->addLayout( l );
 	setLayout( tl );
+	tl->setSizeConstraint(QLayout::SetFixedSize);
 }
 
 

plugins/Compressor/CompressorControlDialog.h

@@ -71,7 +71,6 @@ class CompressorControlDialog : public EffectControlDialog
 public:
 	CompressorControlDialog(CompressorControls* controls);
 
-	bool isResizable() const override {return true;}
 	QSize sizeHint() const override {return QSize(COMP_SCREEN_X, COMP_SCREEN_Y);}
 
 	// For theming purposes

plugins/Dispersion/DispersionControlDialog.cpp

@@ -43,6 +43,7 @@ DispersionControlDialog::DispersionControlDialog(DispersionControls* controls) :
 	setAutoFillBackground(true);
 	auto layout = new QHBoxLayout(this);
 	layout->setSpacing(5);
+	layout->setSizeConstraint(QLayout::SetFixedSize);
 
 	auto amountBox = new LcdSpinBox(3, this, "Amount");
 	amountBox->setModel(&controls->m_amountModel);

plugins/Flanger/FlangerControlsDialog.cpp

@@ -44,6 +44,7 @@ FlangerControlsDialog::FlangerControlsDialog( FlangerControls *controls ) :
 	setPalette( pal );
 
 	auto mainLayout = new QVBoxLayout(this);
+	mainLayout->setSizeConstraint(QLayout::SetFixedSize);
 	auto knobLayout = new QHBoxLayout();
 	mainLayout->addLayout(knobLayout);
 

plugins/LadspaBrowser/LadspaBrowser.cpp

@@ -140,18 +140,13 @@ LadspaBrowserView::LadspaBrowserView( ToolPlugin * _tool ) :
 	hlayout->addWidget( ws );
 	hlayout->addSpacing( 10 );
 	hlayout->addStretch();
+	
+	layout()->setSizeConstraint(QLayout::SetFixedSize);
 
 	hide();
 	if( parentWidget() )
 	{
 		parentWidget()->hide();
-		parentWidget()->layout()->setSizeConstraint(
-							QLayout::SetFixedSize );
-		
-		Qt::WindowFlags flags = parentWidget()->windowFlags();
-		flags |= Qt::MSWindowsFixedSizeDialogHint;
-		flags &= ~Qt::WindowMaximizeButtonHint;
-		parentWidget()->setWindowFlags( flags );
 	}
 }
 

plugins/LadspaEffect/LadspaMatrixControlDialog.cpp

@@ -47,6 +47,7 @@ LadspaMatrixControlDialog::LadspaMatrixControlDialog(LadspaControls * ladspaCont
 	m_stereoLink(nullptr)
 {
 	QVBoxLayout * mainLayout = new QVBoxLayout(this);
+	mainLayout->setSizeConstraint(QLayout::SetMinAndMaxSize);
 
 	m_scrollArea = new QScrollArea(this);
 	m_scrollArea->setWidgetResizable(true);
@@ -72,11 +73,6 @@ LadspaMatrixControlDialog::LadspaMatrixControlDialog(LadspaControls * ladspaCont
 	}
 }
 
-bool LadspaMatrixControlDialog::isResizable() const
-{
-	return true;
-}
-
 bool LadspaMatrixControlDialog::needsLinkColumn() const
 {
 	LadspaControls * ladspaControls = getLadspaControls();

plugins/LadspaEffect/LadspaMatrixControlDialog.h

@@ -50,7 +50,6 @@ class LadspaMatrixControlDialog : public EffectControlDialog
 	Q_OBJECT
 public:
 	LadspaMatrixControlDialog(LadspaControls* ctl);
-	bool isResizable() const override;
 
 private slots:
 	void updateEffectView(LadspaControls* ctl);

plugins/PeakControllerEffect/PeakControllerEffectControlDialog.cpp

@@ -95,6 +95,8 @@ PeakControllerEffectControlDialog::PeakControllerEffectControlDialog(
 	mainLayout->addLayout( knobLayout );
 	mainLayout->addLayout( ledLayout );
 
+	mainLayout->setSizeConstraint(QLayout::SetFixedSize);
+
 	setLayout( mainLayout );
 }
 

plugins/ReverbSC/ReverbSCControlDialog.cpp

@@ -44,6 +44,7 @@ ReverbSCControlDialog::ReverbSCControlDialog( ReverbSCControls* controls ) :
 	setPalette( pal );
 
 	auto knobLayout = new QHBoxLayout(this);
+	knobLayout->setSizeConstraint(QLayout::SetFixedSize);
 
 	auto inputGainKnob = new Knob(KnobType::Bright26, tr("Input"), this);
 	inputGainKnob->setModel( &controls->m_inputGainModel );
@@ -68,4 +69,4 @@ ReverbSCControlDialog::ReverbSCControlDialog( ReverbSCControls* controls ) :
 }
 
 
-} // namespace lmms::gui
+} // namespace lmms::gui

plugins/SpectrumAnalyzer/SaControlsDialog.h

@@ -48,7 +48,6 @@ public:
 	explicit SaControlsDialog(SaControls *controls, SaProcessor *processor);
 	~SaControlsDialog() override = default;
 
-	bool isResizable() const override {return true;}
 	QSize sizeHint() const override;
 
 private:

plugins/StereoEnhancer/StereoEnhancerControlDialog.cpp

@@ -39,6 +39,7 @@ StereoEnhancerControlDialog::StereoEnhancerControlDialog(
 	EffectControlDialog( _controls )
 {
 	auto l = new QHBoxLayout(this);
+	l->setSizeConstraint(QLayout::SetFixedSize);
 
 	auto widthKnob = new Knob(KnobType::Bright26, tr("WIDTH"), this);
 	widthKnob->setModel( &_controls->m_widthModel );

plugins/TapTempo/TapTempoView.cpp

@@ -128,10 +128,10 @@ TapTempoView::TapTempoView(TapTempo* plugin)
 	});
 
 	hide();
+	layout()->setSizeConstraint(QLayout::SetFixedSize);
 	if (parentWidget())
 	{
 		parentWidget()->hide();
-		parentWidget()->layout()->setSizeConstraint(QLayout::SetFixedSize);
 
 		Qt::WindowFlags flags = parentWidget()->windowFlags();
 		flags |= Qt::MSWindowsFixedSizeDialogHint;

plugins/Vectorscope/VecControlsDialog.h

@@ -45,7 +45,6 @@ public:
 	explicit VecControlsDialog(VecControls *controls);
 	~VecControlsDialog() override = default;
 
-	bool isResizable() const override {return true;}
 	QSize sizeHint() const override;
 
 private:

plugins/Vestige/Vestige.cpp

@@ -103,8 +103,9 @@ public:
 	vstSubWin( QWidget * _parent ) :
 		SubWindow( _parent )
 	{
-		setAttribute( Qt::WA_DeleteOnClose, false );
-		setWindowFlags( Qt::WindowCloseButtonHint );
+		setAttribute(Qt::WA_DeleteOnClose, false);
+		setWindowFlag(Qt::WindowMaximizeButtonHint, false);
+		setDetachable(false);
 	}
 
 	~vstSubWin() override = default;
@@ -918,12 +919,9 @@ ManageVestigeInstrumentView::ManageVestigeInstrumentView( Instrument * _instrume
 	widget = new QWidget(this);
 	l = new QGridLayout( this );
 
-	m_vi->m_subWindow = getGUI()->mainWindow()->addWindowedWidget(nullptr, Qt::SubWindow |
-			Qt::CustomizeWindowHint | Qt::WindowTitleHint | Qt::WindowSystemMenuHint);
-	m_vi->m_subWindow->setSizePolicy( QSizePolicy::Fixed, QSizePolicy::MinimumExpanding );
-	m_vi->m_subWindow->setFixedWidth( 960 );
-	m_vi->m_subWindow->setMinimumHeight( 300 );
-	m_vi->m_subWindow->setWidget(m_vi->m_scrollArea);
+	m_vi->m_subWindow = getGUI()->mainWindow()->addWindowedWidget(m_vi->m_scrollArea);
+	m_vi->m_scrollArea->setFixedWidth(960);
+	m_vi->m_scrollArea->setMinimumHeight(300);
 	m_vi->m_subWindow->setWindowTitle( m_vi->instrumentTrack()->name()
 								+ tr( " - VST plugin control" ) );
 	m_vi->m_subWindow->setWindowIcon( PLUGIN_NAME::getIconPixmap( "logo" ) );

plugins/Vestige/Vestige.h

@@ -31,6 +31,7 @@
 
 #include "Instrument.h"
 #include "InstrumentView.h"
+#include "SubWindow.h"
 
 
 class QGridLayout;
@@ -86,7 +87,7 @@ private:
 	QMutex m_pluginMutex;
 
 	QString m_pluginDLL;
-	QMdiSubWindow * m_subWindow;
+	gui::SubWindow* m_subWindow;
 	QScrollArea * m_scrollArea;
 	FloatModel ** knobFModel;
 	QObject * p_subWindow;

src/gui/ControllerDialog.cpp

@@ -23,30 +23,17 @@
  *
  */
 
-#include <QCloseEvent>
-
 #include "ControllerDialog.h"
+
 #include "Controller.h"
 
 namespace lmms::gui
 {
 
-
-ControllerDialog::ControllerDialog( Controller * _controller,
-							QWidget * _parent ) :
-	QWidget( _parent ),
-	ModelView( _controller, this )
+ControllerDialog::ControllerDialog(Controller* controller, QWidget* parent)
+	: QWidget{parent}
+	, ModelView{controller, this}
 {
 }
 
-
-
-void ControllerDialog::closeEvent( QCloseEvent * _ce )
-{
-	_ce->ignore();
-	emit closed();
-}
-
-
-
 } // namespace lmms::gui

src/gui/ControllerRackView.cpp

@@ -45,9 +45,9 @@ namespace lmms::gui
 {
 
 
-ControllerRackView::ControllerRackView() :
-	QWidget(),
-	m_nextIndex(0)
+ControllerRackView::ControllerRackView()
+	: QWidget{}
+	, m_nextIndex{0}
 {
 	setWindowIcon( embed::getIconPixmap( "controller" ) );
 	setWindowTitle( tr( "Controller Rack" ) );
@@ -79,7 +79,10 @@ ControllerRackView::ControllerRackView() :
 	layout->addWidget( m_addButton );
 	this->setLayout( layout );
 
-	QMdiSubWindow * subWin = getGUI()->mainWindow()->addWindowedWidget( this );
+	SubWindow* subWin = getGUI()->mainWindow()->addWindowedWidget(this);
+
+	setFixedWidth(350);
+	setMinimumHeight(200);
 
 	// No maximize button
 	Qt::WindowFlags flags = subWin->windowFlags();
@@ -88,9 +91,6 @@ ControllerRackView::ControllerRackView() :
 	
 	subWin->setAttribute( Qt::WA_DeleteOnClose, false );
 	subWin->move( 680, 310 );
-	subWin->resize( 350, 200 );
-	subWin->setFixedWidth( 350 );
-	subWin->setMinimumHeight( 200 );
 }
 
 
@@ -229,21 +229,4 @@ void ControllerRackView::addController()
 	setFocus();
 }
 
-
-
-
-void ControllerRackView::closeEvent( QCloseEvent * _ce )
- {
-	if( parentWidget() )
-	{
-		parentWidget()->hide();
-	}
-	else
-	{
-		hide();
-	}
-	_ce->ignore();
- }
-
-
 } // namespace lmms::gui

src/gui/ControllerView.cpp

@@ -44,15 +44,14 @@ namespace lmms::gui
 {
 
 
-ControllerView::ControllerView( Controller * _model, QWidget * _parent ) :
-	QFrame( _parent ),
-	ModelView( _model, this ),
-	m_subWindow( nullptr ),
-	m_controllerDlg( nullptr ),
-	m_show( true )
+ControllerView::ControllerView(Controller* model, QWidget* parent)
+	: QFrame{parent}
+	, ModelView{model, this}
+	, m_subWindow{nullptr}
+	, m_controllerDlg{nullptr}
 {
-	this->setFrameStyle( QFrame::StyledPanel );
-	this->setFrameShadow( QFrame::Raised );
+	setFrameStyle(QFrame::StyledPanel);
+	setFrameShadow(QFrame::Raised);
 	setFocusPolicy(Qt::StrongFocus);
 
 	auto vBoxLayout = new QVBoxLayout(this);
@@ -60,7 +59,7 @@ ControllerView::ControllerView( Controller * _model, QWidget * _parent ) :
 	auto hBox = new QHBoxLayout();
 	vBoxLayout->addLayout(hBox);
 
-	auto label = new QLabel("<b>" + _model->displayName() + "</b>", this);
+	auto label = new QLabel("<b>" + model->displayName() + "</b>", this);
 	QSizePolicy sizePolicy = label->sizePolicy();
 	sizePolicy.setHorizontalStretch(1);
 	label->setSizePolicy(sizePolicy);
@@ -72,27 +71,17 @@ ControllerView::ControllerView( Controller * _model, QWidget * _parent ) :
 
 	hBox->addWidget(controlsButton);
 
-	m_nameLabel = new QLabel(_model->name(), this);
+	m_nameLabel = new QLabel(model->name(), this);
 	vBoxLayout->addWidget(m_nameLabel);
 
 
-	m_controllerDlg = getController()->createDialog( getGUI()->mainWindow()->workspace() );
-
-	m_subWindow = getGUI()->mainWindow()->addWindowedWidget( m_controllerDlg );
-	
-	Qt::WindowFlags flags = m_subWindow->windowFlags();
-	flags &= ~Qt::WindowMaximizeButtonHint;
-	m_subWindow->setWindowFlags( flags );
-	m_subWindow->setFixedSize( m_subWindow->size() );
-
-	m_subWindow->setWindowIcon( m_controllerDlg->windowIcon() );
-
-	connect( m_controllerDlg, SIGNAL(closed()),
-		this, SLOT(closeControls()));
+	m_controllerDlg = getController()->createDialog(getGUI()->mainWindow()->workspace());
 
+	m_subWindow = getGUI()->mainWindow()->addWindowedWidget(m_controllerDlg);
+	m_subWindow->setWindowFlag(Qt::WindowMaximizeButtonHint, false);
 	m_subWindow->hide();
 
-	setModel( _model );
+	setModel(model);
 }
 
 
@@ -111,28 +100,20 @@ ControllerView::~ControllerView()
 
 void ControllerView::editControls()
 {
-	if( m_show )
+	if (!m_controllerDlg->isVisible())
 	{
 		m_subWindow->show();
 		m_subWindow->raise();
-		m_show = false;
 	}
 	else
 	{
 		m_subWindow->hide();
-		m_show = true;
 	}
 }
 
 
 
 
-void ControllerView::closeControls()
-{
-	m_subWindow->hide();
-	m_show = true;
-}
-
 void ControllerView::moveUp() { emit movedUp(this); }
 
 void ControllerView::moveDown() { emit movedDown(this); }
@@ -188,4 +169,4 @@ void ControllerView::contextMenuEvent( QContextMenuEvent * )
 }
 
 
-} // namespace lmms::gui
+} // namespace lmms::gui

src/gui/EffectControlDialog.cpp

@@ -23,32 +23,20 @@
  *
  */
 
-#include <QCloseEvent>
-
 #include "EffectControlDialog.h"
+
 #include "EffectControls.h"
 
 namespace lmms::gui
 {
 
-
-EffectControlDialog::EffectControlDialog( EffectControls * _controls ) :
-	QWidget( nullptr ),
-	ModelView( _controls, this ),
-	m_effectControls( _controls )
+EffectControlDialog::EffectControlDialog(EffectControls* controls)
+	: QWidget{nullptr}
+	, ModelView{controls, this}
+	, m_effectControls{controls}
 {
-	setWindowTitle( m_effectControls->effect()->displayName() );
-	setSizePolicy( QSizePolicy::Preferred, QSizePolicy::Preferred );
+	setWindowTitle(m_effectControls->effect()->displayName());
+	setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Preferred);
 }
 
-
-
-
-void EffectControlDialog::closeEvent( QCloseEvent * _ce )
-{
-	_ce->ignore();
-	emit closed();
-}
-
-
 } // namespace lmms::gui

src/gui/EffectView.cpp

@@ -87,26 +87,10 @@ EffectView::EffectView( Effect * _model, QWidget * _parent ) :
 					this, SLOT(editControls()));
 
 		m_controlView = effect()->controls()->createView();
-		if( m_controlView )
+		if (m_controlView)
 		{
-			m_subWindow = getGUI()->mainWindow()->addWindowedWidget( m_controlView );
-
-			if ( !m_controlView->isResizable() )
-			{
-				m_subWindow->setSizePolicy( QSizePolicy::Fixed, QSizePolicy::Fixed );
-				if (m_subWindow->layout())
-				{
-					m_subWindow->layout()->setSizeConstraint(QLayout::SetFixedSize);
-				}
-			}
-
-			Qt::WindowFlags flags = m_subWindow->windowFlags();
-			flags &= ~Qt::WindowMaximizeButtonHint;
-			m_subWindow->setWindowFlags( flags );
-
-			connect( m_controlView, SIGNAL(closed()),
-					this, SLOT(closeEffects()));
-
+			m_subWindow = getGUI()->mainWindow()->addWindowedWidget(m_controlView);
+			m_subWindow->setWindowFlag(Qt::WindowMaximizeButtonHint, false);
 			m_subWindow->hide();
 		}
 	}
@@ -134,11 +118,11 @@ void EffectView::editControls()
 {
 	if( m_subWindow )
 	{
-		if( !m_subWindow->isVisible() )
+		if (!m_controlView->isVisible())
 		{
 			m_subWindow->show();
 			m_subWindow->raise();
-			effect()->controls()->setViewVisible( true );
+			effect()->controls()->setViewVisible(true); // TODO is this even needed?
 		}
 		else
 		{
@@ -174,17 +158,6 @@ void EffectView::deletePlugin()
 
 
 
-void EffectView::closeEffects()
-{
-	if( m_subWindow )
-	{
-		m_subWindow->hide();
-	}
-	effect()->controls()->setViewVisible( false );
-}
-
-
-
 void EffectView::contextMenuEvent( QContextMenuEvent * )
 {
 	QPointer<CaptionMenu> contextMenu = new CaptionMenu( model()->displayName(), this );

src/gui/MainWindow.cpp

@@ -329,15 +329,8 @@ void MainWindow::finalize()
 	m_redoAction = addAction(edit_menu, "edit_redo", tr("Redo"),
 		QKeySequence::Redo, &MainWindow::redo);
 
-	// Ensure that both (Ctrl+Y) and (Ctrl+Shift+Z) activate redo shortcut regardless of OS defaults
-	if (QKeySequence(QKeySequence::Redo) != keySequence(Qt::CTRL, Qt::Key_Y))
-	{
-		new QShortcut(keySequence(Qt::CTRL, Qt::Key_Y), this, SLOT(redo()));
-	}
-	if (QKeySequence(QKeySequence::Redo) != keySequence(Qt::CTRL, Qt::SHIFT, Qt::Key_Z))
-	{
-		new QShortcut(keySequence(Qt::CTRL, Qt::SHIFT, Qt::Key_Z), this, SLOT(redo()));
-	}
+	m_undoAction->setShortcutContext(Qt::ApplicationShortcut);
+	m_redoAction->setShortcutContext(Qt::ApplicationShortcut);
 
 	edit_menu->addSeparator();
 	edit_menu->addAction(embed::getIconPixmap("microtuner"), tr("Scales and keymaps"),
@@ -353,6 +346,7 @@ void MainWindow::finalize()
 		 this, SLOT(updateViewMenu()));
 	connect( m_viewMenu, SIGNAL(triggered(QAction*)), this,
 		SLOT(updateConfig(QAction*)));
+	updateViewMenu();
 
 
 	m_toolsMenu = new QMenu( this );
@@ -493,18 +487,10 @@ void MainWindow::finalize()
 	}
 
 	// Add editor subwindows
-	for (QWidget* widget :  std::list<QWidget*>{
-			getGUI()->automationEditor(),
-			getGUI()->patternEditor(),
-			getGUI()->pianoRoll(),
-			getGUI()->songEditor()
-	})
-	{
-		QMdiSubWindow* window = addWindowedWidget(widget);
-		window->setWindowIcon(widget->windowIcon());
-		window->setAttribute(Qt::WA_DeleteOnClose, false);
-		window->resize(widget->sizeHint());
-	}
+	addWindowedWidget(getGUI()->automationEditor());
+	addWindowedWidget(getGUI()->patternEditor());
+	addWindowedWidget(getGUI()->pianoRoll());
+	addWindowedWidget(getGUI()->songEditor());
 
 	getGUI()->automationEditor()->parentWidget()->hide();
 	getGUI()->patternEditor()->parentWidget()->move(610, 5);
@@ -552,19 +538,35 @@ SubWindow* MainWindow::addWindowedWidget(QWidget *w, Qt::WindowFlags windowFlags
 {
 	// wrap the widget in our own *custom* window that patches some errors in QMdiSubWindow
 	auto win = new SubWindow(m_workspace->viewport(), windowFlags);
-	win->setAttribute(Qt::WA_DeleteOnClose);
+	connect(this, &MainWindow::detachAllSubWindows, win, &SubWindow::setDetached);
 	win->setWidget(w);
-	if (w && w->sizeHint().isValid()) {
-		auto titleBarHeight = win->titleBarHeight();
-		auto frameWidth = win->frameWidth();
-		QSize delta(2* frameWidth, titleBarHeight + frameWidth);
-		win->resize(delta + w->sizeHint());
+
+	if (w)
+	{
+		// TODO: somehow make this work on any setWidget
+		connect(w, &QWidget::destroyed, win, &SubWindow::deleteLater);
+
+		if (w->sizeHint().isValid())
+		{
+			auto titleBarHeight = win->titleBarHeight();
+			auto frameWidth = win->frameWidth();
+			QSize delta(2* frameWidth, titleBarHeight + frameWidth);
+			win->resize(delta + w->sizeHint());
+		}
 	}
+
 	m_workspace->addSubWindow(win);
 	return win;
 }
 
 
+
+void MainWindow::setAllSubWindowsDetached(bool detached)
+{
+	emit detachAllSubWindows(detached);
+}
+
+
 void MainWindow::resetWindowTitle()
 {
 	QString title(tr( "Untitled" ));
@@ -659,77 +661,80 @@ void MainWindow::clearKeyModifiers()
 
 
 
-void MainWindow::saveWidgetState( QWidget * _w, QDomElement & _de )
+void MainWindow::saveWidgetState(QWidget* w, QDomElement& de)
 {
-	// If our widget is the main content of a window (e.g. piano roll, Mixer, etc),
-	// we really care about the position of the *window* - not the position of the widget within its window
-	if( _w->parentWidget() != nullptr &&
-			_w->parentWidget()->inherits( "QMdiSubWindow" ) )
+	// TODO: Only use one of these
+	auto win = qobject_cast<SubWindow*>(w);
+	if (!win)
 	{
-		_w = _w->parentWidget();
+		// Fall back on parent
+		win = qobject_cast<SubWindow*>(w->parentWidget());
+		if (!win)
+		{
+			// Still could not find the window - soft fail
+			return;
+		}
 	}
 
-	// If the widget is a SubWindow, then we can make use of the getTrueNormalGeometry() method that
-	// performs the same as normalGeometry, but isn't broken on X11 ( see https://bugreports.qt.io/browse/QTBUG-256 )
-	auto asSubWindow = qobject_cast<SubWindow*>(_w);
-	QRect normalGeom = asSubWindow != nullptr ? asSubWindow->getTrueNormalGeometry() : _w->normalGeometry();
+	de.setAttribute("visible", bool{win->widget() && win->widget()->isVisible()});
+	de.setAttribute("maximized", win->isMaximized());
 
-	bool visible = _w->isVisible();
-	_de.setAttribute( "visible", visible );
-	_de.setAttribute( "minimized", _w->isMinimized() );
-	_de.setAttribute( "maximized", _w->isMaximized() );
-
-	_de.setAttribute( "x", normalGeom.x() );
-	_de.setAttribute( "y", normalGeom.y() );
-
-	QSize sizeToStore = normalGeom.size();
-	_de.setAttribute( "width", sizeToStore.width() );
-	_de.setAttribute( "height", sizeToStore.height() );
+	QRect normalGeometry = win->getTrueNormalGeometry();
+	de.setAttribute("x", normalGeometry.x());
+	de.setAttribute("y", normalGeometry.y() );
+	de.setAttribute("width", normalGeometry.width());
+	de.setAttribute("height", normalGeometry.height());
 }
 
 
 
 
-void MainWindow::restoreWidgetState( QWidget * _w, const QDomElement & _de )
+void MainWindow::restoreWidgetState(QWidget* w, const QDomElement& de)
 {
-	QRect r( qMax( 1, _de.attribute( "x" ).toInt() ),
-			qMax( 1, _de.attribute( "y" ).toInt() ),
-			qMax( _w->sizeHint().width(), _de.attribute( "width" ).toInt() ),
-			qMax( _w->minimumHeight(), _de.attribute( "height" ).toInt() ) );
-	if( _de.hasAttribute( "visible" ) && !r.isNull() )
+	// TODO: Only use one of these
+	auto win = qobject_cast<SubWindow*>(w);
+	if (!win)
 	{
-		// If our widget is the main content of a window (e.g. piano roll, Mixer, etc),
-		// we really care about the position of the *window* - not the position of the widget within its window
-		if ( _w->parentWidget() != nullptr &&
-			_w->parentWidget()->inherits( "QMdiSubWindow" ) )
+		// Fall back on parent
+		win = qobject_cast<SubWindow*>(w->parentWidget());
+		if (!win)
 		{
-			_w = _w->parentWidget();
+			// Still could not find the window - soft fail
+			return;
 		}
-		// first restore the window, as attempting to resize a maximized window causes graphics glitching
-		_w->setWindowState( _w->windowState() & ~(Qt::WindowMaximized | Qt::WindowMinimized) );
+	}
 
-		// Check isEmpty() to work around corrupt project files with empty size
-		if ( ! r.size().isEmpty() ) {
-			_w->resize( r.size() );
-		}
-		_w->move( r.topLeft() );
+	const auto normalGeometry = QRect {
+		de.attribute("x").toInt(),
+		de.attribute("y").toInt(),
+		de.attribute("width").toInt(),
+		de.attribute("height").toInt()
+	};
+
+	if (normalGeometry.isValid())
+	{
+		// first restore the window, as attempting to resize a maximized window causes graphics glitching
+		win->setWindowState(win->windowState() & ~(Qt::WindowMaximized | Qt::WindowMinimized));
+
+		win->setGeometry(normalGeometry);
 
 		// set the window to its correct minimized/maximized/restored state
-		Qt::WindowStates flags = _w->windowState();
-		flags = _de.attribute( "minimized" ).toInt() ?
-				( flags | Qt::WindowMinimized ) :
-				( flags & ~Qt::WindowMinimized );
-		flags = _de.attribute( "maximized" ).toInt() ?
-				( flags | Qt::WindowMaximized ) :
-				( flags & ~Qt::WindowMaximized );
-		_w->setWindowState( flags );
+		Qt::WindowStates winState = win->windowState();
+		winState = de.attribute("maximized").toInt()
+			? (winState | Qt::WindowMaximized)
+			: (winState & ~Qt::WindowMaximized);
+		win->setWindowState(winState);
+	}
 
-		_w->setVisible( _de.attribute( "visible" ).toInt() );
+	if (const auto visible = de.attribute("visible"); !visible.isEmpty())
+	{
+		win->setVisible(visible.toInt());
 	}
 }
 
 
 
+
 void MainWindow::emptySlot()
 {
 }
@@ -1086,6 +1091,22 @@ void MainWindow::updateViewMenu()
 
 	m_viewMenu->addSeparator();
 
+	auto detachAllAction = m_viewMenu->addAction(embed::getIconPixmap("detach"),
+		tr("Detach all subwindows"),
+		this, [this](){ setAllSubWindowsDetached(true); },
+		QKeySequence{Qt::CTRL | Qt::SHIFT | Qt::Key_D}
+	);
+	auto attachAllAction = m_viewMenu->addAction(embed::getIconPixmap("detach"),
+		tr("Attach all subwindows"),
+		this, [this](){ setAllSubWindowsDetached(false); },
+		QKeySequence{Qt::CTRL | Qt::ALT | Qt::SHIFT | Qt::Key_D}
+	);
+
+	detachAllAction->setShortcutContext(Qt::ApplicationShortcut);
+	attachAllAction->setShortcutContext(Qt::ApplicationShortcut);
+
+	m_viewMenu->addSeparator();
+
 	// Here we should put all look&feel -stuff from configmanager
 	// that is safe to change on the fly. There is probably some
 	// more elegant way to do this.

src/gui/MicrotunerConfig.cpp

@@ -192,13 +192,10 @@ MicrotunerConfig::MicrotunerConfig() :
 	this->setLayout(microtunerLayout);
 
 	// Add to the main window and setup fixed size etc.
-	QMdiSubWindow *subWin = getGUI()->mainWindow()->addWindowedWidget(this);
-
+	SubWindow* subWin = getGUI()->mainWindow()->addWindowedWidget(this);
 	subWin->setAttribute(Qt::WA_DeleteOnClose, false);
-	subWin->setMinimumWidth(300);
-	subWin->setMinimumHeight(300);
-	subWin->setMaximumWidth(500);
-	subWin->setMaximumHeight(700);
+	setMinimumSize(300, 300);
+	setMaximumSize(500, 700);
 	subWin->hide();
 
 	// No maximize button
@@ -654,12 +651,4 @@ void MicrotunerConfig::loadSettings(const QDomElement &element)
 }
 
 
-void MicrotunerConfig::closeEvent(QCloseEvent *ce)
-{
-	if (parentWidget()) {parentWidget()->hide();}
-	else {hide();}
-	ce->ignore();
-}
-
-
 } // namespace lmms::gui

src/gui/MidiCCRackView.cpp

@@ -49,7 +49,7 @@ MidiCCRackView::MidiCCRackView(InstrumentTrack * track) :
 	setWindowIcon(embed::getIconPixmap("midi_cc_rack"));
 	setWindowTitle(tr("MIDI CC Rack - %1").arg(m_track->name()));
 
-	QMdiSubWindow * subWin = getGUI()->mainWindow()->addWindowedWidget(this);
+	SubWindow* subWin = getGUI()->mainWindow()->addWindowedWidget(this);
 
 	// Remove maximize button
 	Qt::WindowFlags flags = subWin->windowFlags();
@@ -58,9 +58,8 @@ MidiCCRackView::MidiCCRackView(InstrumentTrack * track) :
 
 	// Adjust window attributes, sizing and position
 	subWin->setAttribute(Qt::WA_DeleteOnClose, false);
-	subWin->resize(350, 300);
-	subWin->setFixedWidth(350);
-	subWin->setMinimumHeight(300);
+	setFixedWidth(350);
+	setMinimumHeight(300);
 	subWin->hide();
 
 	// Main window layout

src/gui/MixerView.cpp

@@ -162,10 +162,10 @@ MixerView::MixerView(Mixer* mixer) :
 	// timer for updating faders
 	connect(mainWindow, &MainWindow::periodicUpdate, this, &MixerView::updateFaders);
 
-	// add ourself to workspace
-	QMdiSubWindow* subWin = mainWindow->addWindowedWidget(this);
 	layout()->setSizeConstraint(QLayout::SetMinimumSize);
-	subWin->layout()->setSizeConstraint(QLayout::SetMinAndMaxSize);
+
+	// add ourself to workspace
+	mainWindow->addWindowedWidget(this);
 
 	parentWidget()->setAttribute(Qt::WA_DeleteOnClose, false);
 	parentWidget()->move(5, 310);
@@ -532,21 +532,6 @@ void MixerView::keyPressEvent(QKeyEvent * e)
 
 
 
-void MixerView::closeEvent(QCloseEvent * ce)
- {
-	if (parentWidget())
-	{
-		parentWidget()->hide();
-	}
-	else
-	{
-		hide();
-	}
-	ce->ignore();
- }
-
-
-
 void MixerView::setCurrentMixerChannel(int channel)
 {
 	if (channel >= 0 && channel < m_mixerChannelViews.size())

src/gui/ProjectNotes.cpp

@@ -28,7 +28,6 @@
 #include <QAction>
 #include <QActionGroup>
 #include <QApplication>
-#include <QCloseEvent>
 #include <QColorDialog>
 #include <QComboBox>
 #include <QFontDatabase>
@@ -50,8 +49,8 @@ namespace lmms::gui
 {
 
 
-ProjectNotes::ProjectNotes() :
-	QMainWindow( getGUI()->mainWindow()->workspace() )
+ProjectNotes::ProjectNotes()
+	: QMainWindow{getGUI()->mainWindow()->workspace()}
 {
 	m_edit = new QTextEdit( this );
 	m_edit->setAutoFillBackground( true );
@@ -391,20 +390,4 @@ void ProjectNotes::loadSettings( const QDomElement & _this )
 	m_edit->setHtml( _this.text() );
 }
 
-
-
-
-void ProjectNotes::closeEvent( QCloseEvent * _ce )
-{
-	if( parentWidget() )
-	{
-		parentWidget()->hide();
-	}
-	else
-	{
-		hide();
-	}
-	_ce->ignore();
- }
-
 } // namespace lmms::gui

src/gui/SampleTrackWindow.cpp

@@ -47,11 +47,11 @@ namespace lmms::gui
 {
 
 
-SampleTrackWindow::SampleTrackWindow(SampleTrackView * tv) :
-	QWidget(),
-	ModelView(nullptr, this),
-	m_track(tv->model()),
-	m_stv(tv)
+SampleTrackWindow::SampleTrackWindow(SampleTrackView* stv)
+	: QWidget{}
+	, ModelView{nullptr, this}
+	, m_track{stv->model()}
+	, m_stv{stv}
 {
 	// init own layout + widgets
 	setFocusPolicy(Qt::StrongFocus);
@@ -148,29 +148,25 @@ SampleTrackWindow::SampleTrackWindow(SampleTrackView * tv) :
 
 	generalSettingsLayout->addLayout(basicControlsLayout);
 
-	m_effectRack = new EffectRackView(tv->model()->audioBusHandle()->effects());
+	m_effectRack = new EffectRackView(stv->model()->audioBusHandle()->effects());
 	m_effectRack->setFixedSize(EffectRackView::DEFAULT_WIDTH, 242);
 
 	vlayout->addWidget(generalSettingsWidget);
 	vlayout->addWidget(m_effectRack);
 
 
-	setModel(tv->model());
+	setModel(stv->model());
 
 	QMdiSubWindow * subWin = getGUI()->mainWindow()->addWindowedWidget(this);
 	Qt::WindowFlags flags = subWin->windowFlags();
-	flags |= Qt::MSWindowsFixedSizeDialogHint;
+	flags |= Qt::MSWindowsFixedSizeDialogHint;  // resizing is disabled regardless, this makes SubWindow hide related actions
 	flags &= ~Qt::WindowMaximizeButtonHint;
 	subWin->setWindowFlags(flags);
 
-	// Hide the Size and Maximize options from the system menu
-	// since the dialog size is fixed.
-	QMenu * systemMenu = subWin->systemMenu();
-	systemMenu->actions().at(2)->setVisible(false); // Size
-	systemMenu->actions().at(4)->setVisible(false); // Maximize
+	// better than `setFixedSize` because it still responds to layout changes
+	layout()->setSizeConstraint(QLayout::SetFixedSize);
 
-	subWin->setWindowIcon(embed::getIconPixmap("sample_track"));
-	subWin->setFixedSize(subWin->size());
+	setWindowIcon(embed::getIconPixmap("sample_track"));
 	subWin->hide();
 }
 
@@ -247,27 +243,15 @@ void SampleTrackWindow::toggleVisibility(bool on)
 
 void SampleTrackWindow::closeEvent(QCloseEvent* ce)
 {
-	ce->ignore();
-
-	if(getGUI()->mainWindow()->workspace())
-	{
-		parentWidget()->hide();
-	}
-	else
-	{
-		hide();
-	}
-
 	m_stv->setFocus();
 	m_stv->m_tlb->setChecked(false);
 }
 
 
 
-void SampleTrackWindow::saveSettings(QDomDocument& doc, QDomElement & element)
+void SampleTrackWindow::saveSettings(QDomDocument& doc, QDomElement& element)
 {
 	MainWindow::saveWidgetState(this, element);
-	Q_UNUSED(element)
 }
 
 

src/gui/SubWindow.cpp

@@ -28,25 +28,34 @@
 
 #include "SubWindow.h"
 
+#include <algorithm>
+
 #include <QGraphicsDropShadowEffect>
+#include <QGuiApplication>
 #include <QLabel>
+#include <QLayout>
 #include <QMdiArea>
+#include <QMetaMethod>
 #include <QMoveEvent>
 #include <QPainter>
 #include <QPushButton>
+#include <QStyleOption>
 #include <QStyleOptionTitleBar>
+#include <QWindow>
 
+#include "ConfigManager.h"
 #include "embed.h"
 
 namespace lmms::gui
 {
 
 
-SubWindow::SubWindow(QWidget *parent, Qt::WindowFlags windowFlags) :
-	QMdiSubWindow(parent, windowFlags),
-	m_buttonSize(17, 17),
-	m_titleBarHeight(titleBarHeight()),
-	m_hasFocus(false)
+SubWindow::SubWindow(QWidget* parent, Qt::WindowFlags windowFlags)
+	: QMdiSubWindow{parent, windowFlags}
+	, m_buttonSize{17, 17}
+	, m_titleBarHeight{titleBarHeight()}
+	, m_hasFocus{false}
+	, m_isDetachable{true}
 {
 	// initialize the tracked geometry to whatever Qt thinks the normal geometry currently is.
 	// this should always work, since QMdiSubWindows will not start as maximized
@@ -57,15 +66,27 @@ SubWindow::SubWindow(QWidget *parent, Qt::WindowFlags windowFlags) :
 	m_textShadowColor = Qt::black;
 	m_borderColor = Qt::black;
 
-	// close, maximize and restore (after maximizing) buttons
-	m_closeBtn = addTitleButton("close", tr("Close"));
-	connect( m_closeBtn, SIGNAL(clicked(bool)), this, SLOT(close()));
+	// close, maximize, restore, and detach buttons
+	auto createButton = [this](std::string_view iconName, const QString& tooltip) -> QPushButton* {
+		auto button = new QPushButton{embed::getIconPixmap(iconName), QString{}, this};
+		button->resize(m_buttonSize);
+		button->setFocusPolicy(Qt::NoFocus);
+		button->setCursor(Qt::ArrowCursor);
+		button->setAttribute(Qt::WA_NoMousePropagation);
+		button->setToolTip(tooltip);
+		return button;
+	};
+	m_closeBtn = createButton("close", tr("Close"));
+	connect(m_closeBtn, &QPushButton::clicked, this, &QWidget::close);
 
-	m_maximizeBtn = addTitleButton("maximize", tr("Maximize"));
-	connect( m_maximizeBtn, SIGNAL(clicked(bool)), this, SLOT(showMaximized()));
+	m_maximizeBtn = createButton("maximize", tr("Maximize"));
+	connect(m_maximizeBtn, &QPushButton::clicked, this, &QWidget::showMaximized);
 
-	m_restoreBtn = addTitleButton("restore", tr("Restore"));
-	connect( m_restoreBtn, SIGNAL(clicked(bool)), this, SLOT(showNormal()));
+	m_restoreBtn = createButton("restore", tr("Restore"));
+	connect(m_restoreBtn, &QPushButton::clicked, this, &QWidget::showNormal);
+
+	m_detachBtn = createButton("detach", tr("Detach"));
+	connect(m_detachBtn, &QPushButton::clicked, this, &SubWindow::detach);
 
 	// QLabel for the window title and the shadow effect
 	m_shadow = new QGraphicsDropShadowEffect();
@@ -78,6 +99,8 @@ SubWindow::SubWindow(QWidget *parent, Qt::WindowFlags windowFlags) :
 	m_windowTitle->setAttribute( Qt::WA_TransparentForMouseEvents, true );
 	m_windowTitle->setGraphicsEffect( m_shadow );
 
+	layout()->setSizeConstraint(QLayout::SetMinAndMaxSize);
+
 	// Disable the minimize button and make sure that the custom window hint is set
 	setWindowFlags((this->windowFlags() & ~Qt::WindowMinimizeButtonHint) | Qt::CustomizeWindowHint);
 
@@ -139,7 +162,60 @@ void SubWindow::changeEvent( QEvent *event )
 	{
 		adjustTitleBar();
 	}
+}
 
+
+
+
+void SubWindow::setVisible(bool visible)
+{
+	if (isDetached() || visible) { widget()->setVisible(visible); }
+	if (!isDetached()) { QMdiSubWindow::setVisible(visible); }
+}
+
+
+
+
+void SubWindow::showEvent(QShowEvent* e)
+{
+	if (ConfigManager::inst()->value("ui", "detachbehavior", "show") == "detached") { detach(); }
+	if (isDetached())
+	{
+		widget()->setWindowState((widget()->windowState() & ~Qt::WindowMinimized) | Qt::WindowActive);
+	}
+}
+
+
+
+
+bool SubWindow::isDetachable() const
+{
+	return m_isDetachable;
+}
+
+
+
+
+void SubWindow::setDetachable(bool on)
+{
+	m_isDetachable = on;
+}
+
+
+
+
+bool SubWindow::isDetached() const
+{
+	return widget()->windowFlags().testFlag(Qt::Window);
+}
+
+
+
+
+void SubWindow::setDetached(bool on)
+{
+	if (on) { detach(); }
+	else { attach(); }
 }
 
 
@@ -228,6 +304,73 @@ void SubWindow::setBorderColor( const QColor &c )
 
 
 
+void SubWindow::detach()
+{
+	if (!isDetachable() || isDetached()) { return; }
+
+	const auto pos = mapToGlobal(widget()->pos());
+	const bool shown = isVisible();
+
+	auto flags = windowFlags();
+	flags |= Qt::Window;
+	flags &= ~Qt::SubWindow;
+	flags |= Qt::WindowMinimizeButtonHint;
+
+	hide();
+	widget()->setWindowFlags(flags);
+
+	if (shown) { widget()->show(); }
+
+	widget()->move(pos);
+}
+
+void SubWindow::attach()
+{
+	if (!isDetached()) { return; }
+
+	const bool shown = widget()->isVisible();
+
+	auto frame = widget()->geometry();
+	frame.moveTo(mdiArea()->mapFromGlobal(frame.topLeft()));
+	frame += decorationMargins();
+
+	// Make sure the window fully fits on screen
+	frame.setSize({
+		std::min(frame.width(), mdiArea()->width()),
+		std::min(frame.height(), mdiArea()->height())
+	});
+
+	frame.moveTo(
+		std::clamp(frame.left(), 0, mdiArea()->rect().width() - frame.width()),
+		std::clamp(frame.top(), 0, mdiArea()->rect().height() - frame.height())
+	);
+
+	auto flags = windowFlags();
+	flags &= ~Qt::Window;
+	flags |= Qt::SubWindow;
+	flags &= ~Qt::WindowMinimizeButtonHint;
+	widget()->setWindowFlags(flags);
+
+	if (shown)
+	{
+		widget()->show();
+		show();
+	}
+
+	if (QGuiApplication::platformName() == "wayland")
+	{
+		// Workaround for wayland reporting position as 0-0
+		// See https://doc.qt.io/qt-6.9/application-windows.html#wayland-peculiarities
+		resize(frame.size());
+	}
+	else
+	{
+		setGeometry(frame);
+	}
+}
+
+
+
 int SubWindow::titleBarHeight() const
 {
 	QStyleOptionTitleBar so;
@@ -246,6 +389,21 @@ int SubWindow::frameWidth() const
 }
 
 
+
+
+QMargins SubWindow::decorationMargins() const
+{
+	return {
+		frameWidth(),     // left
+		titleBarHeight(), // top
+		frameWidth(),     // right
+		frameWidth()      // bottom
+	};
+}
+
+
+
+
 void SubWindow::updateTitleBar()
 {
 	adjustTitleBar();
@@ -306,15 +464,15 @@ void SubWindow::adjustTitleBar()
 	// button adjustments
 	m_maximizeBtn->hide();
 	m_restoreBtn->hide();
+	m_detachBtn->hide();
 	m_closeBtn->show();
 
 	const int rightSpace = 3;
 	const int buttonGap = 1;
 	const int menuButtonSpace = 24;
 
-	QPoint rightButtonPos( width() - rightSpace - m_buttonSize.width(), 3 );
-	QPoint middleButtonPos( width() - rightSpace - ( 2 * m_buttonSize.width() ) - buttonGap, 3 );
-	QPoint leftButtonPos( width() - rightSpace - ( 3 * m_buttonSize.width() ) - ( 2 * buttonGap ), 3 );
+	auto buttonPos = QPoint{width() - rightSpace - m_buttonSize.width(), 3};
+	const auto buttonStep = QPoint{m_buttonSize.width() + buttonGap, 0};
 
 	// the buttonBarWidth depends on the number of buttons.
 	// we need it to calculate the width of window title label
@@ -322,24 +480,36 @@ void SubWindow::adjustTitleBar()
 
 	// set the buttons on their positions.
 	// the close button is always needed and on the rightButtonPos
-	m_closeBtn->move( rightButtonPos );
+	m_closeBtn->move(buttonPos);
+	buttonPos -= buttonStep;
 
 	// here we ask: is the Subwindow maximizable and
 	// then we set the buttons and show them if needed
 	if( windowFlags() & Qt::WindowMaximizeButtonHint )
 	{
 		buttonBarWidth = buttonBarWidth + m_buttonSize.width() + buttonGap;
-		m_maximizeBtn->move( middleButtonPos );
-		m_restoreBtn->move( middleButtonPos );
-		m_maximizeBtn->setVisible(true);
+		m_maximizeBtn->move(buttonPos);
+		m_restoreBtn->move(buttonPos);
+		if (!isMaximized())
+		{
+			m_maximizeBtn->show();
+			buttonPos -= buttonStep;
+		}
 	}
 
 	// we're keeping the restore button around if we open projects
 	// from older versions that have saved minimized windows
-	m_restoreBtn->setVisible(isMinimized());
-	if( isMinimized() )
+	if (isMinimized())
 	{
-		m_restoreBtn->move( m_maximizeBtn->isHidden() ?  middleButtonPos : leftButtonPos );
+		m_restoreBtn->show();
+		buttonPos -= buttonStep;
+	}
+
+	if (isDetachable())
+	{
+		m_detachBtn->move(buttonPos);
+		m_detachBtn->show();
+		buttonBarWidth = buttonBarWidth + m_buttonSize.width() + buttonGap;
 	}
 
 	if( widget() )
@@ -412,16 +582,63 @@ void SubWindow::resizeEvent( QResizeEvent * event )
 	}
 }
 
-QPushButton* SubWindow::addTitleButton(const std::string& iconName, const QString& toolTip)
-{
-	auto button = new QPushButton(embed::getIconPixmap(iconName), QString(), this);
-	button->resize(m_buttonSize);
-	button->setFocusPolicy(Qt::NoFocus);
-	button->setCursor(Qt::ArrowCursor);
-	button->setAttribute(Qt::WA_NoMousePropagation);
-	button->setToolTip(toolTip);
 
-	return button;
+
+
+/**
+ * @brief SubWindow::eventFilter
+ *
+ * Override of QMdiSubWindow's event filter.
+ * This is not how regular eventFilters work, it is never installed explicitly.
+ * Instead, it is installed by Qt and conveniently installs itself
+ * onto the child widget. Despite relying on internal implementation details,
+ * as of writing this it seems to be the best way to do so as soon as the widget is set.
+ */
+bool SubWindow::eventFilter(QObject* obj, QEvent* event)
+{
+	if (obj != static_cast<QObject*>(widget()))
+	{
+		return QMdiSubWindow::eventFilter(obj, event);
+	}
+
+	switch (event->type())
+	{
+		case QEvent::WindowStateChange:
+			event->accept();
+			return true;
+
+		case QEvent::Close:
+			if (isDetached())
+			{
+				QString detachBehavior = ConfigManager::inst()->value("ui", "detachbehavior", "show");
+				if (detachBehavior == "show")
+				{
+					attach();
+					event->ignore();
+					return true;
+				}
+				else if (detachBehavior == "hide")
+				{
+					attach();
+					hide();
+					event->ignore();
+					return QMdiSubWindow::eventFilter(obj, event);
+				}
+				else if (detachBehavior == "detached")
+				{
+					event->accept();
+					return QMdiSubWindow::eventFilter(obj, event);
+				}
+			}
+			else
+			{
+				hide();
+			}
+			return QMdiSubWindow::eventFilter(obj, event);
+
+		default:
+			return QMdiSubWindow::eventFilter(obj, event);
+	}
 }
 
 

src/gui/editors/Editor.cpp

@@ -24,18 +24,15 @@
 
 #include "Editor.h"
 
+#include <QAction>
+#include <QShortcut>
+
 #include "DeprecationHelper.h"
 #include "GuiApplication.h"
 #include "MainWindow.h"
 #include "Song.h"
-
 #include "embed.h"
 
-#include <QAction>
-#include <QShortcut>
-#include <QCloseEvent>
-
-
 namespace lmms::gui
 {
 
@@ -92,6 +89,7 @@ void Editor::toggleMaximize()
 }
 
 Editor::Editor(bool record, bool stepRecord) :
+	QMainWindow(),
 	m_toolBar(new DropToolBar(this)),
 	m_playAction(nullptr),
 	m_recordAction(nullptr),
@@ -141,22 +139,8 @@ QAction *Editor::playAction() const
 	return m_playAction;
 }
 
-void Editor::closeEvent(QCloseEvent * event)
+void Editor::keyPressEvent(QKeyEvent* ke)
 {
-	if( parentWidget() )
-	{
-		parentWidget()->hide();
-	}
-	else
-	{
-		hide();
-	}
-	getGUI()->mainWindow()->refocus();
-	event->ignore();
- }
-
- void Editor::keyPressEvent(QKeyEvent *ke)
- {
 	if (ke->key() == Qt::Key_Space)
 	{
 		if (ke->modifiers() & Qt::ShiftModifier)
@@ -170,7 +154,7 @@ void Editor::closeEvent(QCloseEvent * event)
 		return;
 	}
 	ke->ignore();
- }
+}
 
 DropToolBar::DropToolBar(QWidget* parent) : QToolBar(parent)
 {

src/gui/editors/SongEditor.cpp

@@ -572,21 +572,6 @@ void SongEditor::wheelEvent( QWheelEvent * we )
 
 
 
-void SongEditor::closeEvent( QCloseEvent * ce )
-{
-	if( parentWidget() )
-	{
-		parentWidget()->hide();
-	}
-	else
-	{
-		hide();
-	}
-	ce->ignore();
-}
-
-
-
 
 void SongEditor::mousePressEvent(QMouseEvent *me)
 {

src/gui/instrument/InstrumentTrackWindow.cpp

@@ -293,7 +293,6 @@ InstrumentTrackWindow::InstrumentTrackWindow( InstrumentTrackView * _itv ) :
 	// we can reuse this method.
 	updateSubWindow();
 
-	subWin->setWindowIcon(embed::getIconPixmap("instrument_track"));
 	subWin->hide();
 }
 
@@ -530,6 +529,7 @@ void InstrumentTrackWindow::toggleVisibility( bool on )
 	else
 	{
 		parentWidget()->hide();
+		hide();
 	}
 }
 
@@ -538,17 +538,6 @@ void InstrumentTrackWindow::toggleVisibility( bool on )
 
 void InstrumentTrackWindow::closeEvent( QCloseEvent* event )
 {
-	event->ignore();
-
-	if( getGUI()->mainWindow()->workspace() )
-	{
-		parentWidget()->hide();
-	}
-	else
-	{
-		hide();
-	}
-
 	m_itv->setFocus();
 	m_itv->m_tlb->setChecked(false);
 }
@@ -620,6 +609,7 @@ void InstrumentTrackWindow::dropEvent( QDropEvent* event )
 		event->accept();
 		setFocus();
 	}
+	updateSubWindow();
 }
 
 
@@ -679,13 +669,34 @@ void InstrumentTrackWindow::viewInstrumentInDirection(int d)
 	// avoid reloading the window if there is only one instrument, as that will just change the active tab
 	if (idxOfNext != idxOfMe)
 	{
+		const auto sourceSubwin = static_cast<SubWindow*>(parentWidget());
+		const auto targetSubwin = static_cast<SubWindow*>(newView->getInstrumentTrackWindow()->parentWidget());
+		QWidget* sourceWidget;
+		QWidget* targetWidget;
+
+		// set widgets we move and get our position from
+		if (sourceSubwin->isDetached())
+		{
+			sourceWidget = this;
+			targetWidget = newView->getInstrumentTrackWindow();
+		}
+		else
+		{
+			sourceWidget = parentWidget();
+			targetWidget = newView->getInstrumentTrackWindow()->parentWidget();
+		}
+
 		// save current window pos and then hide the window by unchecking its button in the track list
-		QPoint curPos = parentWidget()->pos();
+		QPoint curPos = sourceWidget->pos();
 		m_itv->m_tlb->setChecked(false);
 
 		// enable the new window by checking its track list button & moving it to where our window just was
 		newView->m_tlb->setChecked(true);
-		newView->getInstrumentTrackWindow()->parentWidget()->move(curPos);
+
+		// sync detached state with current widget like we do with position
+		targetSubwin->setDetached(sourceSubwin->isDetached());
+
+		targetWidget->move(curPos);
 
 		// scroll the SongEditor/PatternEditor to make sure the new trackview label is visible
 		bringToFront->trackContainerView()->scrollToTrackView(bringToFront);
@@ -695,13 +706,8 @@ void InstrumentTrackWindow::viewInstrumentInDirection(int d)
 	}
 	Q_ASSERT(bringToFront);
 	bringToFront->getInstrumentTrackWindow()->setFocus();
-	Qt::WindowFlags flags = windowFlags();
-	if (!m_instrumentView->isResizable()) {
-		flags |= Qt::MSWindowsFixedSizeDialogHint;
-	} else {
-		flags &= ~Qt::MSWindowsFixedSizeDialogHint;
-	}
-	setWindowFlags( flags );
+
+	updateSubWindow();
 }
 
 void InstrumentTrackWindow::viewNextInstrument()
@@ -748,24 +754,19 @@ void InstrumentTrackWindow::updateSubWindow()
 	auto subWindow = findSubWindowInParents();
 	if (subWindow && m_instrumentView)
 	{
-		Qt::WindowFlags flags = subWindow->windowFlags();
-
 		const auto instrumentViewResizable = m_instrumentView->isResizable();
 
 		if (instrumentViewResizable)
 		{
 			// TODO As of writing SlicerT is the only resizable instrument. Is this code specific to SlicerT?
+			// TODO Expand extraSpace in terms of specific widget sizes or replace with QLayout::setSizeConstraint.
 			const auto extraSpace = QSize(12, 208);
-			subWindow->setMaximumSize(m_instrumentView->maximumSize() + extraSpace);
-			subWindow->setMinimumSize(m_instrumentView->minimumSize() + extraSpace);
-
-			flags &= ~Qt::MSWindowsFixedSizeDialogHint;
-			flags |= Qt::WindowMaximizeButtonHint;
+			setMaximumSize(m_instrumentView->maximumSize() + extraSpace);
+			setMinimumSize(m_instrumentView->minimumSize() + extraSpace);
 		}
 		else
 		{
-			flags |= Qt::MSWindowsFixedSizeDialogHint;
-			flags &= ~Qt::WindowMaximizeButtonHint;
+			setFixedSize(sizeHint());
 
 			// The sub window might be reused from an instrument that was maximized. Show the sub window
 			// as normal, i.e. not maximized, if the instrument view is not resizable.
@@ -775,13 +776,8 @@ void InstrumentTrackWindow::updateSubWindow()
 			}
 		}
 
-		subWindow->setWindowFlags(flags);
+		subWindow->setWindowFlag(Qt::WindowMaximizeButtonHint, instrumentViewResizable);
 
-		// Show or hide the Size and Maximize options from the system menu depending on whether the view is resizable or not
-		QMenu * systemMenu = subWindow->systemMenu();
-		systemMenu->actions().at(2)->setVisible(instrumentViewResizable); // Size
-		systemMenu->actions().at(4)->setVisible(instrumentViewResizable); // Maximize
-		
 		// TODO This is only needed if the sub window is implemented with LMMS' own SubWindow class.
 		// If an QMdiSubWindow is used everything works automatically. It seems that SubWindow is
 		// missing some implementation details that QMdiSubWindow has.

src/gui/modals/SetupDialog.cpp

@@ -119,6 +119,7 @@ SetupDialog::SetupDialog(ConfigTab tab_to_open) :
 			"app", "disablebackup").toInt()),
 	m_openLastProject(ConfigManager::inst()->value(
 			"app", "openlastproject").toInt()),
+	m_detachBehavior{ConfigManager::inst()->value("ui", "detachbehavior", "show")},
 	m_loopMarkerMode{ConfigManager::inst()->value("app", "loopmarkermode", "dual")},
 	m_autoScroll(ConfigManager::inst()->value("ui", "autoscroll", "stepped")),
 	m_lang(ConfigManager::inst()->value(
@@ -257,6 +258,19 @@ SetupDialog::SetupDialog(ConfigTab tab_to_open) :
 	addCheckBox(tr("Show warning when deleting a mixer channel that is in use"), guiGroupBox, guiGroupLayout,
 		m_mixerChannelDeletionWarning,	SLOT(toggleMixerChannelDeletionWarning(bool)), false);
 
+	m_detachBehaviorComboBox = new QComboBox{guiGroupBox};
+
+	m_detachBehaviorComboBox->addItem(tr("Attach and show when closed"), "show");
+	m_detachBehaviorComboBox->addItem(tr("Attach and hide when closed"), "hide");
+	m_detachBehaviorComboBox->addItem(tr("Always detached"), "detached");
+
+	m_detachBehaviorComboBox->setCurrentIndex(m_detachBehaviorComboBox->findData(m_detachBehavior));
+	connect(m_detachBehaviorComboBox, qOverload<int>(&QComboBox::currentIndexChanged),
+		this, &SetupDialog::detachBehaviorChanged);
+
+	guiGroupLayout->addWidget(new QLabel{tr("Detached window behavior"), guiGroupBox});
+	guiGroupLayout->addWidget(m_detachBehaviorComboBox);
+
 	m_loopMarkerComboBox = new QComboBox{guiGroupBox};
 
 	m_loopMarkerComboBox->addItem(tr("Dual-button"), "dual");
@@ -991,6 +1005,7 @@ void SetupDialog::accept()
 					QString::number(!m_disableBackup));
 	ConfigManager::inst()->setValue("app", "openlastproject",
 					QString::number(m_openLastProject));
+	ConfigManager::inst()->setValue("ui", "detachbehavior", m_detachBehavior);
 	ConfigManager::inst()->setValue("app", "loopmarkermode", m_loopMarkerMode);
 	ConfigManager::inst()->setValue("app", "language", m_lang);
 	ConfigManager::inst()->setValue("ui", "autoscroll", m_autoScroll);
@@ -1131,6 +1146,12 @@ void SetupDialog::toggleOpenLastProject(bool enabled)
 }
 
 
+void SetupDialog::detachBehaviorChanged()
+{
+	m_detachBehavior = m_detachBehaviorComboBox->currentData().toString();
+}
+
+
 void SetupDialog::loopMarkerModeChanged()
 {
 	m_loopMarkerMode = m_loopMarkerComboBox->currentData().toString();

src/gui/tracks/InstrumentTrackView.cpp

@@ -24,6 +24,8 @@
 
 #include "InstrumentTrackView.h"
 
+#include <ranges>
+
 #include <QAction>
 #include <QApplication>
 #include <QDragEnterEvent>
@@ -205,20 +207,21 @@ void InstrumentTrackView::toggleMidiCCRack()
 
 
 
-InstrumentTrackWindow * InstrumentTrackView::topLevelInstrumentTrackWindow()
+InstrumentTrackWindow* InstrumentTrackView::topLevelInstrumentTrackWindow()
 {
-	InstrumentTrackWindow * w = nullptr;
-	for( const QMdiSubWindow * sw :
-				getGUI()->mainWindow()->workspace()->subWindowList(
-											QMdiArea::ActivationHistoryOrder ) )
+	const auto subWindows = getGUI()->mainWindow()->workspace()->subWindowList(QMdiArea::ActivationHistoryOrder);
+
+	for (QMdiSubWindow* sw : subWindows | std::views::reverse)
 	{
-		if( sw->isVisible() && sw->widget()->inherits( "lmms::gui::InstrumentTrackWindow" ) )
+		if (!sw->widget() || !sw->widget()->isVisible()) { continue; }
+
+		if (auto itw = qobject_cast<InstrumentTrackWindow*>(sw->widget()))
 		{
-			w = qobject_cast<InstrumentTrackWindow *>( sw->widget() );
+			return itw;
 		}
 	}
 
-	return w;
+	return nullptr;
 }
 
 

src/gui/widgets/TempoSyncBarModelEditor.cpp

@@ -205,11 +205,11 @@ void TempoSyncBarModelEditor::showCustom()
 	if(m_custom == nullptr)
 	{
 		m_custom = new MeterDialog(getGUI()->mainWindow()->workspace());
-		QMdiSubWindow * subWindow = getGUI()->mainWindow()->addWindowedWidget(m_custom);
+		SubWindow* subWindow = getGUI()->mainWindow()->addWindowedWidget(m_custom);
 		Qt::WindowFlags flags = subWindow->windowFlags();
 		flags &= ~Qt::WindowMaximizeButtonHint;
 		subWindow->setWindowFlags(flags);
-		subWindow->setFixedSize(subWindow->size());
+		setFixedSize(size());
 		m_custom->setWindowTitle("Meter");
 		m_custom->setModel(&model()->getCustomMeterModel());
 	}

src/gui/widgets/TempoSyncKnob.cpp

@@ -315,11 +315,11 @@ void TempoSyncKnob::showCustom()
 	if( m_custom == nullptr )
 	{
 		m_custom = new MeterDialog( getGUI()->mainWindow()->workspace() );
-		QMdiSubWindow * subWindow = getGUI()->mainWindow()->addWindowedWidget( m_custom );
+		SubWindow* subWindow = getGUI()->mainWindow()->addWindowedWidget(m_custom);
 		Qt::WindowFlags flags = subWindow->windowFlags();
 		flags &= ~Qt::WindowMaximizeButtonHint;
 		subWindow->setWindowFlags( flags );
-		subWindow->setFixedSize( subWindow->size() );
+		setFixedSize(size());
 		m_custom->setWindowTitle( "Meter" );
 		m_custom->setModel( &model()->m_custom );
 	}