diff --git a/.travis/debian_pkgs.sha256 b/.travis/debian_pkgs.sha256
index 96a4bd8aa..ed4e11737 100644
--- a/.travis/debian_pkgs.sha256
+++ b/.travis/debian_pkgs.sha256
@@ -1,2 +1,3 @@
 314ef4af137903dfb13e8c3ef1e6ea56cfdb23808d52ec4f5f50e288c73610c5  pbuilder_0.229.1_all.deb
 fa82aa8ed3055c6f6330104deedf080b26778295e589426d4c4dd0f2c2a5defa  debootstrap_1.0.95_all.deb
+2ef4c09f7841b72f93412803ddd142f72658536dbfabe00e449eb548f432f3f8  debian-archive-keyring_2017.7ubuntu1_all.deb
diff --git a/.travis/linux.debian-sid.install.sh b/.travis/linux.debian-sid.install.sh
index ecdcf6d91..ef8368822 100755
--- a/.travis/linux.debian-sid.install.sh
+++ b/.travis/linux.debian-sid.install.sh
@@ -2,15 +2,16 @@
 set -e
 
 sudo apt-get install -y \
-	debian-archive-keyring \
 	dpkg \
 	pbuilder
 
 # work around a pbuilder bug which breaks ccache
 # https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=666525
+# and also missing signing keys in Trusty's debian-archive-keyring
 cd /tmp
 wget http://archive.ubuntu.com/ubuntu/pool/main/p/pbuilder/pbuilder_0.229.1_all.deb
 wget http://archive.ubuntu.com/ubuntu/pool/main/d/debootstrap/debootstrap_1.0.95_all.deb
+wget http://archive.ubuntu.com/ubuntu/pool/universe/d/debian-archive-keyring/debian-archive-keyring_2017.7ubuntu1_all.deb
 sha256sum -c "$TRAVIS_BUILD_DIR/.travis/debian_pkgs.sha256"
-sudo dpkg -i pbuilder_0.229.1_all.deb debootstrap_1.0.95_all.deb
+sudo dpkg -i pbuilder_0.229.1_all.deb debootstrap_1.0.95_all.deb debian-archive-keyring_2017.7ubuntu1_all.deb
 cd "$OLDPWD"
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7a39d7d9f..0f9d66def 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -157,7 +157,7 @@ SET(QT_LIBRARIES
 	Qt5::Xml
 )
 
-IF(LMMS_BUILD_LINUX)
+IF(LMMS_BUILD_LINUX AND WANT_VST)
     FIND_PACKAGE(Qt5 COMPONENTS X11Extras REQUIRED)
     LIST(APPEND QT_LIBRARIES Qt5::X11Extras)
 ENDIF()
diff --git a/cmake/linux/package_linux.sh.in b/cmake/linux/package_linux.sh.in
index ba6c7279a..0dec715f4 100644
--- a/cmake/linux/package_linux.sh.in
+++ b/cmake/linux/package_linux.sh.in
@@ -74,8 +74,10 @@ else
 	success "Downloaded $LINUXDEPLOYQT"
 	# Extract AppImage and replace LINUXDEPLOYQT variable with extracted binary
 	# to support systems without fuse
+	# Also, we need to set LD_LIBRARY_PATH, but linuxdepoyqt's AppRun unsets it
+	# See https://github.com/probonopd/linuxdeployqt/pull/370/
 	"$LINUXDEPLOYQT" --appimage-extract > /dev/null 2>&1
-	LINUXDEPLOYQT="squashfs-root/AppRun"
+	LINUXDEPLOYQT="squashfs-root/usr/bin/linuxdeployqt"
 	success "Extracted $APPIMAGETOOL"
 fi
 
diff --git a/doc/wiki b/doc/wiki
index 42193f98f..19179c6f6 160000
--- a/doc/wiki
+++ b/doc/wiki
@@ -1 +1 @@
-Subproject commit 42193f98f37d6b69f47edbdfd50a20090193e70a
+Subproject commit 19179c6f6afb422cf8376ed3b4a498a6396fc12f
diff --git a/include/AutomatableModel.h b/include/AutomatableModel.h
index 78f4882b4..3e0b6143d 100644
--- a/include/AutomatableModel.h
+++ b/include/AutomatableModel.h
@@ -33,6 +33,7 @@
 #include "MidiTime.h"
 #include "ValueBuffer.h"
 #include "MemoryManager.h"
+#include "ModelVisitor.h"
 
 // simple way to map a property of a view to a model
 #define mapPropertyFromModelPtr(type,getfunc,setfunc,modelname)	\
@@ -59,6 +60,11 @@
 				modelname.setValue( (float) val );				\
 			}
 
+// use this to make subclasses visitable
+#define MODEL_IS_VISITABLE \
+	void accept(ModelVisitor& v) override { v.visit(*this); } \
+	void accept(ConstModelVisitor& v) const override { v.visit(*this); }
+
 
 
 class ControllerConnection;
@@ -68,6 +74,7 @@ class LMMS_EXPORT AutomatableModel : public Model, public JournallingObject
 	Q_OBJECT
 	MM_OPERATORS
 public:
+
 	typedef QVector<AutomatableModel *> AutoModelVector;
 
 	enum ScaleType
@@ -80,6 +87,35 @@ public:
 
 	virtual ~AutomatableModel();
 
+	// Implement those by using the MODEL_IS_VISITABLE macro
+	virtual void accept(ModelVisitor& v) = 0;
+	virtual void accept(ConstModelVisitor& v) const = 0;
+
+public:
+	/**
+	   @brief Return this class casted to Target
+	   @test AutomatableModelTest.cpp
+	   @param doThrow throw an assertion if the cast fails, instead of
+	     returning a nullptr
+	   @return the casted class if Target is the exact or a base class of
+	     *this, nullptr otherwise
+	*/
+	template<class Target>
+	Target* dynamicCast(bool doThrow = false)
+	{
+		DCastVisitor<Target> vis; accept(vis);
+		if (doThrow && !vis.result) { Q_ASSERT(false); }
+		return vis.result;
+	}
+
+	//! const overload, see overloaded function
+	template<class Target>
+	const Target* dynamicCast(bool doThrow = false) const
+	{
+		ConstDCastVisitor<Target> vis; accept(vis);
+		if (doThrow && !vis.result) { Q_ASSERT(false); }
+		return vis.result;
+	}
 
 	bool isAutomated() const;
 	bool isAutomatedOrControlled() const
@@ -283,6 +319,22 @@ protected:
 
 
 private:
+	// dynamicCast implementation
+	template<class Target>
+	struct DCastVisitor : public ModelVisitor
+	{
+		Target* result = nullptr;
+		void visit(Target& tar) { result = &tar; }
+	};
+
+	// dynamicCast implementation
+	template<class Target>
+	struct ConstDCastVisitor : public ConstModelVisitor
+	{
+		const Target* result = nullptr;
+		void visit(const Target& tar) { result = &tar; }
+	};
+
 	static bool mustQuoteName(const QString &name);
 
 	virtual void saveSettings( QDomDocument& doc, QDomElement& element )
@@ -382,6 +434,7 @@ public:
 class LMMS_EXPORT FloatModel : public TypedAutomatableModel<float>
 {
 	Q_OBJECT
+	MODEL_IS_VISITABLE
 public:
 	FloatModel( float val = 0, float min = 0, float max = 0, float step = 0,
 				Model * parent = NULL,
@@ -399,6 +452,7 @@ public:
 class LMMS_EXPORT IntModel : public TypedAutomatableModel<int>
 {
 	Q_OBJECT
+	MODEL_IS_VISITABLE
 public:
 	IntModel( int val = 0, int min = 0, int max = 0,
 				Model* parent = NULL,
@@ -414,6 +468,7 @@ public:
 class LMMS_EXPORT BoolModel : public TypedAutomatableModel<bool>
 {
 	Q_OBJECT
+	MODEL_IS_VISITABLE
 public:
 	BoolModel( const bool val = false,
 				Model* parent = NULL,
diff --git a/include/ComboBoxModel.h b/include/ComboBoxModel.h
index ad3603759..82c01e69e 100644
--- a/include/ComboBoxModel.h
+++ b/include/ComboBoxModel.h
@@ -36,6 +36,7 @@
 class LMMS_EXPORT ComboBoxModel : public IntModel
 {
 	Q_OBJECT
+	MODEL_IS_VISITABLE
 public:
 	ComboBoxModel( Model* parent = NULL,
 					const QString& displayName = QString(),
diff --git a/include/Effect.h b/include/Effect.h
index 3d765fdc0..4dc50e8a4 100644
--- a/include/Effect.h
+++ b/include/Effect.h
@@ -161,6 +161,13 @@ public:
 
 
 protected:
+	/**
+		Effects should call this at the end of audio processing
+
+		If the setting "Keep effects running even without input" is disabled,
+		after "decay" ms of a signal below "gate", the effect is turned off
+		and won't be processed again until it receives new audio input
+	*/
 	void checkGate( double _out_sum );
 
 	virtual PluginView * instantiateView( QWidget * );
diff --git a/include/FileBrowser.h b/include/FileBrowser.h
index 7e0482ce3..4b92dd549 100644
--- a/include/FileBrowser.h
+++ b/include/FileBrowser.h
@@ -55,7 +55,7 @@ public:
 
 private slots:
 	void reloadTree( void );
-	void expandItems( QTreeWidgetItem * item=NULL );
+	void expandItems( QTreeWidgetItem * item=NULL, QList<QString> expandedDirs = QList<QString>() );
 	// call with item=NULL to filter the entire tree
 	bool filterItems( const QString & filter, QTreeWidgetItem * item=NULL );
 	void giveFocusToFilter();
@@ -87,6 +87,10 @@ public:
 	FileBrowserTreeWidget( QWidget * parent );
 	virtual ~FileBrowserTreeWidget() = default;
 
+	//! This method returns a QList with paths (QString's) of all directories
+	//! that are expanded in the tree.
+	QList<QString> expandedDirs( QTreeWidgetItem * item = nullptr ) const;
+
 
 protected:
 	virtual void contextMenuEvent( QContextMenuEvent * e );
diff --git a/include/Graph.h b/include/Graph.h
index 4827bda40..1bee05c41 100644
--- a/include/Graph.h
+++ b/include/Graph.h
@@ -44,13 +44,18 @@ class LMMS_EXPORT Graph : public QWidget, public ModelView
 public:
 	enum graphStyle
 	{
-		NearestStyle,
-		LinearStyle,
-		LinearNonCyclicStyle,
-		BarStyle,
+		NearestStyle, //!< draw as stairs
+		LinearStyle, //!< connect each 2 samples with a line, with wrapping
+		LinearNonCyclicStyle, //!< LinearStyle without wrapping
+		BarStyle, //!< draw thick bars
 		NumGraphStyles
 	};
 
+	/**
+	 * @brief Constructor
+	 * @param _width Pixel width of widget
+	 * @param _height Pixel height of widget
+	 */
 	Graph( QWidget * _parent, graphStyle _style = Graph::LinearStyle,
 		int _width = 132,
 		int _height = 104
@@ -111,10 +116,24 @@ private:
 } ;
 
 
+/**
+	@brief 2 dimensional function plot
+
+	Function plot graph with discrete x scale and continous y scale
+	This makes it possible to display "#x" samples
+*/
 class LMMS_EXPORT graphModel : public Model
 {
 	Q_OBJECT
 public:
+	/**
+	 * @brief Constructor
+	 * @param _min Minimum y value to display
+	 * @param _max Maximum y value to display
+	 * @param _size Number of samples (e.g. x value)
+	 * @param _step Step size on y axis where values snap to, or 0.0f
+	 *   for "no snapping"
+	 */
 	graphModel( float _min,
 			float _max,
 			int _size,
@@ -146,14 +165,21 @@ public:
 		return( m_samples.data() );
 	}
 
-	void convolve(const float *convolution, const int convolutionLength, const int centerOffset);
+	//! Make cyclic convolution
+	//! @param convolution Samples to convolve with
+	//! @param convolutionLength Number of samples to take for each sum
+	//! @param centerOffset Offset for resulting values
+	void convolve(const float *convolution,
+		const int convolutionLength, const int centerOffset);
 
 public slots:
+	//! Set range of y values
 	void setRange( float _min, float _max );
 
 	void setLength( int _size );
-
+	//! Update one sample
 	void setSampleAt( int x, float val );
+	//! Update samples array
 	void setSamples( const float * _value );
 
 	void setWaveToSine();
diff --git a/include/InstrumentTrack.h b/include/InstrumentTrack.h
index 6a2cacb3a..c487438d0 100644
--- a/include/InstrumentTrack.h
+++ b/include/InstrumentTrack.h
@@ -431,6 +431,9 @@ protected slots:
 private:
 	virtual void modelChanged();
 	void viewInstrumentInDirection(int d);
+	//! adjust size of any child widget of the main tab
+	//! required to keep the old look when using a variable sized tab widget
+	void adjustTabSize(QWidget *w);
 
 	InstrumentTrack * m_track;
 	InstrumentTrackView * m_itv;
diff --git a/include/ModelVisitor.h b/include/ModelVisitor.h
new file mode 100644
index 000000000..f9d156e30
--- /dev/null
+++ b/include/ModelVisitor.h
@@ -0,0 +1,64 @@
+/*
+ * ModelVisitor.h - visitors for automatable models
+ *
+ * Copyright (c) 2019-2019 Johannes Lorenz <j.git$$$lorenz-ho.me, $$$=@>
+ *
+ * This file is part of LMMS - https://lmms.io
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program 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
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program (see COPYING); if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA.
+ *
+ */
+
+#ifndef MODELVISITOR_H
+#define MODELVISITOR_H
+
+class AutomatableModel;
+class BoolModel;
+class IntModel;
+class FloatModel;
+class ComboBoxModel;
+class TempoSyncKnobModel;
+
+class ModelVisitor
+{
+	template<class ParentType = AutomatableModel, class ModelType>
+	void up(ModelType& m) { visit(static_cast<ParentType&>(m)); }
+public:
+	virtual void visit(AutomatableModel& ) {}
+	virtual void visit(BoolModel& m);
+	virtual void visit(IntModel& m);
+	virtual void visit(FloatModel& m);
+	virtual void visit(ComboBoxModel& m);
+	virtual void visit(TempoSyncKnobModel& m);
+	virtual ~ModelVisitor();
+};
+
+class ConstModelVisitor
+{
+	template<class ParentType = AutomatableModel, class ModelType>
+	void up(const ModelType& m) {
+		visit(static_cast<const ParentType&>(m)); }
+public:
+	virtual void visit(const AutomatableModel& ) {}
+	virtual void visit(const BoolModel& m);
+	virtual void visit(const IntModel& m);
+	virtual void visit(const FloatModel& m);
+	virtual void visit(const ComboBoxModel& m);
+	virtual void visit(const TempoSyncKnobModel& m);
+	virtual ~ConstModelVisitor();
+};
+
+#endif // MODELVISITOR_H
diff --git a/include/NotePlayHandle.h b/include/NotePlayHandle.h
index c94a69c2c..ae55c9ebb 100644
--- a/include/NotePlayHandle.h
+++ b/include/NotePlayHandle.h
@@ -303,6 +303,7 @@ private:
 	NotePlayHandleList m_subNotes;			// used for chords and arpeggios
 	volatile bool m_released;				// indicates whether note is released
 	bool m_releaseStarted;
+	bool m_hasMidiNote;
 	bool m_hasParent;						// indicates whether note has parent
 	NotePlayHandle * m_parent;			// parent note
 	bool m_hadChildren;
diff --git a/include/PianoRoll.h b/include/PianoRoll.h
index b4115b054..4451a07c5 100644
--- a/include/PianoRoll.h
+++ b/include/PianoRoll.h
@@ -296,6 +296,8 @@ private:
 	void testPlayNote( Note * n );
 	void testPlayKey( int _key, int _vol, int _pan );
 	void pauseTestNotes(bool pause = true );
+	void playChordNotes(int key, int velocity=-1);
+	void pauseChordNotes(int key);
 
 	QList<int> getAllOctavesForKey( int keyToMirror ) const;
 
diff --git a/include/PluginIssue.h b/include/PluginIssue.h
new file mode 100644
index 000000000..c00945805
--- /dev/null
+++ b/include/PluginIssue.h
@@ -0,0 +1,66 @@
+/*
+ * PluginIssue.h - PluginIssue class
+ *
+ * Copyright (c) 2019 Johannes Lorenz <j.git$$$lorenz-ho.me, $$$=@>
+ *
+ * This file is part of LMMS - https://lmms.io
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program 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
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program (see COPYING); if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA.
+ *
+ */
+
+#ifndef PLUGINISSUE_H
+#define PLUGINISSUE_H
+
+#include <QDebug>
+#include <string>
+
+//! Types of issues that can cause LMMS to not load a plugin
+//! LMMS Plugins should use this to indicate errors
+enum PluginIssueType
+{
+	unknownPortFlow,
+	unknownPortType,
+	tooManyInputChannels,
+	tooManyOutputChannels,
+	noOutputChannel,
+	portHasNoDef,
+	portHasNoMin,
+	portHasNoMax,
+	featureNotSupported, //!< plugin requires functionality LMMS can't offer
+	badPortType, //!< port type not supported
+	noIssue
+};
+
+//! Issue type bundled with informational string
+class PluginIssue
+{
+	static const char* msgFor(const PluginIssueType& it);
+
+	PluginIssueType m_issueType;
+	std::string m_info;
+
+public:
+	PluginIssue(PluginIssueType it, std::string msg = std::string())
+		: m_issueType(it), m_info(msg)
+	{
+	}
+	friend QDebug operator<<(QDebug stream, const PluginIssue& iss);
+};
+
+QDebug operator<<(QDebug stream, const PluginIssue& iss);
+
+#endif // PLUGINISSUE_H
diff --git a/include/TabWidget.h b/include/TabWidget.h
index dacd2648b..11e4da40a 100644
--- a/include/TabWidget.h
+++ b/include/TabWidget.h
@@ -36,7 +36,10 @@ class TabWidget : public QWidget
 {
 	Q_OBJECT
 public:
-	TabWidget( const QString & _caption, QWidget * _parent, bool usePixmap = false );
+	//! @param resizable If true, the widget resizes to fit the size of all tabs
+	//!   If false, all child widget will be cut down to the TabWidget's size
+	TabWidget( const QString & _caption, QWidget * _parent,
+				bool usePixmap = false, bool resizable = false );
 	virtual ~TabWidget() = default;
 
 	void addTab( QWidget * w, const QString & name, const char *pixmap = NULL, int idx = -1 );
@@ -74,7 +77,7 @@ protected:
 	virtual void paintEvent( QPaintEvent * _pe );
 	virtual void resizeEvent( QResizeEvent * _re );
 	virtual void wheelEvent( QWheelEvent * _we );
-
+	virtual QSize minimumSizeHint() const;
 
 private:
 	struct widgetDesc
@@ -88,6 +91,7 @@ private:
 
 	widgetStack m_widgets;
 
+	bool	m_resizable;
 	int 	m_activeTab;
 	QString m_caption;      // Tab caption, used as the tooltip text on icon tabs
 	quint8 	m_tabbarHeight; // The height of the tab bar
diff --git a/include/TempoSyncKnobModel.h b/include/TempoSyncKnobModel.h
index 9a8ad619c..9aaf48fea 100644
--- a/include/TempoSyncKnobModel.h
+++ b/include/TempoSyncKnobModel.h
@@ -33,6 +33,7 @@ class QAction;
 class LMMS_EXPORT TempoSyncKnobModel : public FloatModel
 {
 	Q_OBJECT
+	MODEL_IS_VISITABLE
 public:
 	enum TempoSyncMode
 	{
@@ -51,10 +52,10 @@ public:
 				const float _max, const float _step,
 				const float _scale, Model * _parent,
 				const QString & _display_name = QString() );
-	virtual ~TempoSyncKnobModel();
+	virtual ~TempoSyncKnobModel() override;
 
-	void saveSettings( QDomDocument & _doc, QDomElement & _this, const QString& name );
-	void loadSettings( const QDomElement & _this, const QString& name );
+	void saveSettings( QDomDocument & _doc, QDomElement & _this, const QString& name ) override;
+	void loadSettings( const QDomElement & _this, const QString& name ) override;
 
 	TempoSyncMode syncMode() const
 	{
diff --git a/plugins/Eq/EqControlsDialog.cpp b/plugins/Eq/EqControlsDialog.cpp
index af2378a2c..00c8eaaa7 100644
--- a/plugins/Eq/EqControlsDialog.cpp
+++ b/plugins/Eq/EqControlsDialog.cpp
@@ -55,10 +55,10 @@ EqControlsDialog::EqControlsDialog( EqControls *controls ) :
 
 	EqSpectrumView * inSpec = new EqSpectrumView( &controls->m_inFftBands, this );
 	inSpec->move( 26, 17 );
-	inSpec->setColor( QColor( 54, 45, 142, 150 ) );
+	inSpec->setColor( QColor( 77, 101, 242, 150 ) );
 
 	EqSpectrumView * outSpec = new EqSpectrumView( &controls->m_outFftBands, this );
-	outSpec->setColor( QColor( 9, 166, 156, 150 ) );
+	outSpec->setColor( QColor( 0, 255, 239, 150 ) );
 	outSpec->move( 26, 17 );
 
 	m_parameterWidget = new EqParameterWidget( this , controls );
diff --git a/plugins/LadspaEffect/LadspaControls.cpp b/plugins/LadspaEffect/LadspaControls.cpp
index 8e65e0e93..028394d30 100644
--- a/plugins/LadspaEffect/LadspaControls.cpp
+++ b/plugins/LadspaEffect/LadspaControls.cpp
@@ -36,7 +36,8 @@ LadspaControls::LadspaControls( LadspaEffect * _eff ) :
 {
 
 	connect( &m_stereoLinkModel, SIGNAL( dataChanged() ),
-				this, SLOT( updateLinkStatesFromGlobal() ) );
+				this, SLOT( updateLinkStatesFromGlobal() ),
+				Qt::DirectConnection );
 
 	multi_proc_t controls = m_effect->getPortControls();
 	m_controlCount = controls.count();
@@ -59,7 +60,8 @@ LadspaControls::LadspaControls( LadspaEffect * _eff ) :
 				if( linked_control )
 				{
 					connect( (*it)->control, SIGNAL( linkChanged( int, bool ) ),
-								this, SLOT( linkPort( int, bool ) ) );
+								this, SLOT( linkPort( int, bool ) ),
+								Qt::DirectConnection );
 				}
 			}
 		}
diff --git a/plugins/VstEffect/VstEffect.cpp b/plugins/VstEffect/VstEffect.cpp
index cbb30e2fe..80f209a7b 100644
--- a/plugins/VstEffect/VstEffect.cpp
+++ b/plugins/VstEffect/VstEffect.cpp
@@ -145,9 +145,6 @@ void VstEffect::openPlugin( const QString & _plugin )
 		return;
 	}
 
-	VstPlugin::connect( Engine::getSong(), SIGNAL( tempoChanged( bpm_t ) ), m_plugin.data(), SLOT( setTempo( bpm_t ) ) );
-	m_plugin->setTempo( Engine::getSong()->getTempo() );
-
 	delete tf;
 
 	m_key.attributes["file"] = _plugin;
diff --git a/plugins/vst_base/RemoteVstPlugin.cpp b/plugins/vst_base/RemoteVstPlugin.cpp
index 3526b27cc..48ab13743 100644
--- a/plugins/vst_base/RemoteVstPlugin.cpp
+++ b/plugins/vst_base/RemoteVstPlugin.cpp
@@ -1962,7 +1962,8 @@ DWORD WINAPI RemoteVstPlugin::processingThread( LPVOID _param )
         {
 		if( m.id == IdStartProcessing
 			|| m.id == IdMidiEvent
-			|| m.id == IdVstSetParameter )
+			|| m.id == IdVstSetParameter
+			|| m.id == IdVstSetTempo )
 		{
 			_this->processMessage( m );
 		}
diff --git a/plugins/vst_base/VstPlugin.cpp b/plugins/vst_base/VstPlugin.cpp
index 9f468087c..f224f092d 100644
--- a/plugins/vst_base/VstPlugin.cpp
+++ b/plugins/vst_base/VstPlugin.cpp
@@ -162,7 +162,7 @@ VstPlugin::VstPlugin( const QString & _plugin ) :
 	setTempo( Engine::getSong()->getTempo() );
 
 	connect( Engine::getSong(), SIGNAL( tempoChanged( bpm_t ) ),
-			this, SLOT( setTempo( bpm_t ) ) );
+			this, SLOT( setTempo( bpm_t ) ), Qt::DirectConnection );
 	connect( Engine::mixer(), SIGNAL( sampleRateChanged() ),
 				this, SLOT( updateSampleRate() ) );
 
diff --git a/src/3rdparty/CMakeLists.txt b/src/3rdparty/CMakeLists.txt
index b40f7c3cd..473e7702f 100644
--- a/src/3rdparty/CMakeLists.txt
+++ b/src/3rdparty/CMakeLists.txt
@@ -3,7 +3,7 @@ set(CMAKE_CXX_FLAGS "")
 set(CMAKE_C_FLAGS_DEBUG "")
 set(CMAKE_CXX_FLAGS_DEBUG "")
 
-IF(LMMS_BUILD_LINUX)
+IF(LMMS_BUILD_LINUX AND WANT_VST)
 	set(BUILD_SHARED_LIBS OFF)
 	add_subdirectory(qt5-x11embed)
 ENDIF()
diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
index 7870415f9..ba41e089c 100644
--- a/src/core/CMakeLists.txt
+++ b/src/core/CMakeLists.txt
@@ -40,6 +40,7 @@ set(LMMS_SRCS
 	core/MixerWorkerThread.cpp
 	core/MixHelpers.cpp
 	core/Model.cpp
+	core/ModelVisitor.cpp
 	core/Note.cpp
 	core/NotePlayHandle.cpp
 	core/Oscillator.cpp
@@ -48,6 +49,7 @@ set(LMMS_SRCS
 	core/Piano.cpp
 	core/PlayHandle.cpp
 	core/Plugin.cpp
+	core/PluginIssue.cpp
 	core/PluginFactory.cpp
 	core/PresetPreviewPlayHandle.cpp
 	core/ProjectJournal.cpp
diff --git a/src/core/ControllerConnection.cpp b/src/core/ControllerConnection.cpp
index 45e36e12f..4d43a4366 100644
--- a/src/core/ControllerConnection.cpp
+++ b/src/core/ControllerConnection.cpp
@@ -205,7 +205,7 @@ void ControllerConnection::loadSettings( const QDomElement & _this )
 	else
 	{
 		m_controllerId = _this.attribute( "id", "-1" ).toInt();
-		if( m_controllerId < 0 )
+		if( m_controllerId < 0 || m_controllerId >= Engine::getSong()->controllers().size() )
 		{
 			qWarning( "controller index invalid\n" );
 			m_controllerId = -1;
diff --git a/src/core/EnvelopeAndLfoParameters.cpp b/src/core/EnvelopeAndLfoParameters.cpp
index 9001cd796..27a73b2c1 100644
--- a/src/core/EnvelopeAndLfoParameters.cpp
+++ b/src/core/EnvelopeAndLfoParameters.cpp
@@ -131,32 +131,32 @@ EnvelopeAndLfoParameters::EnvelopeAndLfoParameters(
 	instances()->add( this );
 
 	connect( &m_predelayModel, SIGNAL( dataChanged() ),
-			this, SLOT( updateSampleVars() ) );
+			this, SLOT( updateSampleVars() ), Qt::DirectConnection );
 	connect( &m_attackModel, SIGNAL( dataChanged() ),
-			this, SLOT( updateSampleVars() ) );
+			this, SLOT( updateSampleVars() ), Qt::DirectConnection );
 	connect( &m_holdModel, SIGNAL( dataChanged() ),
-			this, SLOT( updateSampleVars() ) );
+			this, SLOT( updateSampleVars() ), Qt::DirectConnection );
 	connect( &m_decayModel, SIGNAL( dataChanged() ),
-			this, SLOT( updateSampleVars() ) );
+			this, SLOT( updateSampleVars() ), Qt::DirectConnection );
 	connect( &m_sustainModel, SIGNAL( dataChanged() ),
-			this, SLOT( updateSampleVars() ) );
+			this, SLOT( updateSampleVars() ), Qt::DirectConnection );
 	connect( &m_releaseModel, SIGNAL( dataChanged() ),
-			this, SLOT( updateSampleVars() ) );
+			this, SLOT( updateSampleVars() ), Qt::DirectConnection );
 	connect( &m_amountModel, SIGNAL( dataChanged() ),
-			this, SLOT( updateSampleVars() ) );
+			this, SLOT( updateSampleVars() ), Qt::DirectConnection );
 
 	connect( &m_lfoPredelayModel, SIGNAL( dataChanged() ),
-			this, SLOT( updateSampleVars() ) );
+			this, SLOT( updateSampleVars() ), Qt::DirectConnection );
 	connect( &m_lfoAttackModel, SIGNAL( dataChanged() ),
-			this, SLOT( updateSampleVars() ) );
+			this, SLOT( updateSampleVars() ), Qt::DirectConnection );
 	connect( &m_lfoSpeedModel, SIGNAL( dataChanged() ),
-			this, SLOT( updateSampleVars() ) );
+			this, SLOT( updateSampleVars() ), Qt::DirectConnection );
 	connect( &m_lfoAmountModel, SIGNAL( dataChanged() ),
-			this, SLOT( updateSampleVars() ) );
+			this, SLOT( updateSampleVars() ), Qt::DirectConnection );
 	connect( &m_lfoWaveModel, SIGNAL( dataChanged() ),
-			this, SLOT( updateSampleVars() ) );
+			this, SLOT( updateSampleVars() ), Qt::DirectConnection );
 	connect( &m_x100Model, SIGNAL( dataChanged() ),
-				this, SLOT( updateSampleVars() ) );
+			this, SLOT( updateSampleVars() ), Qt::DirectConnection );
 
 	connect( Engine::mixer(), SIGNAL( sampleRateChanged() ),
 				this, SLOT( updateSampleVars() ) );
diff --git a/src/core/LadspaControl.cpp b/src/core/LadspaControl.cpp
index cf8c6e468..731241b85 100644
--- a/src/core/LadspaControl.cpp
+++ b/src/core/LadspaControl.cpp
@@ -42,7 +42,8 @@ LadspaControl::LadspaControl( Model * _parent, port_desc_t * _port,
 	if( m_link )
 	{
 		connect( &m_linkEnabledModel, SIGNAL( dataChanged() ),
-					 this, SLOT( linkStateChanged() ) );
+					 this, SLOT( linkStateChanged() ),
+					 Qt::DirectConnection );
 	}
 
 	switch( m_port->data_type )
diff --git a/src/core/LfoController.cpp b/src/core/LfoController.cpp
index c1c81119f..2b2db2f14 100644
--- a/src/core/LfoController.cpp
+++ b/src/core/LfoController.cpp
@@ -49,12 +49,12 @@ LfoController::LfoController( Model * _parent ) :
 {
 	setSampleExact( true );
 	connect( &m_waveModel, SIGNAL( dataChanged() ),
-			this, SLOT( updateSampleFunction() ) );
+			this, SLOT( updateSampleFunction() ), Qt::DirectConnection );
 
 	connect( &m_speedModel, SIGNAL( dataChanged() ),
-			this, SLOT( updateDuration() ) );
+			this, SLOT( updateDuration() ), Qt::DirectConnection );
 	connect( &m_multiplierModel, SIGNAL( dataChanged() ),
-			this, SLOT( updateDuration() ) );
+			this, SLOT( updateDuration() ), Qt::DirectConnection );
 	connect( Engine::mixer(), SIGNAL( sampleRateChanged() ),
 			this, SLOT( updateDuration() ) );
 
diff --git a/src/core/MeterModel.cpp b/src/core/MeterModel.cpp
index 87b1b950a..30db26d9b 100644
--- a/src/core/MeterModel.cpp
+++ b/src/core/MeterModel.cpp
@@ -33,9 +33,9 @@ MeterModel::MeterModel( ::Model * _parent ) :
 	m_denominatorModel( 4, 1, 32, this, tr( "Denominator" ) )
 {
 	connect( &m_numeratorModel, SIGNAL( dataChanged() ), 
-				this, SIGNAL( dataChanged() ) );
+			this, SIGNAL( dataChanged() ), Qt::DirectConnection );
 	connect( &m_denominatorModel, SIGNAL( dataChanged() ), 
-				this, SIGNAL( dataChanged() ) );
+			this, SIGNAL( dataChanged() ), Qt::DirectConnection );
 }
 
 
diff --git a/src/core/ModelVisitor.cpp b/src/core/ModelVisitor.cpp
new file mode 100644
index 000000000..4036f56e0
--- /dev/null
+++ b/src/core/ModelVisitor.cpp
@@ -0,0 +1,44 @@
+/*
+ * ModelVisitor.cpp - visitors for automatable models
+ *
+ * Copyright (c) 2019-2019 Johannes Lorenz <j.git$$$lorenz-ho.me, $$$=@>
+ *
+ * This file is part of LMMS - https://lmms.io
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program 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
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program (see COPYING); if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include "ModelVisitor.h"
+
+#include "AutomatableModel.h"
+#include "ComboBoxModel.h"
+#include "TempoSyncKnobModel.h"
+
+void ModelVisitor::visit(BoolModel &m) { up(m); }
+void ModelVisitor::visit(IntModel &m) { up(m); }
+void ModelVisitor::visit(FloatModel &m) { up(m); }
+void ModelVisitor::visit(ComboBoxModel &m) { up<IntModel>(m); }
+void ModelVisitor::visit(TempoSyncKnobModel &m) { up<FloatModel>(m); }
+
+void ConstModelVisitor::visit(const BoolModel &m) { up(m); }
+void ConstModelVisitor::visit(const IntModel &m) { up(m); }
+void ConstModelVisitor::visit(const FloatModel &m) { up(m); }
+void ConstModelVisitor::visit(const ComboBoxModel &m) { up<IntModel>(m); }
+void ConstModelVisitor::visit(const TempoSyncKnobModel &m) { up<FloatModel>(m); }
+
+ModelVisitor::~ModelVisitor() {}
+ConstModelVisitor::~ConstModelVisitor() {}
diff --git a/src/core/NotePlayHandle.cpp b/src/core/NotePlayHandle.cpp
index 8c838f136..67b7b416a 100644
--- a/src/core/NotePlayHandle.cpp
+++ b/src/core/NotePlayHandle.cpp
@@ -62,6 +62,7 @@ NotePlayHandle::NotePlayHandle( InstrumentTrack* instrumentTrack,
 	m_subNotes(),
 	m_released( false ),
 	m_releaseStarted( false ),
+	m_hasMidiNote( false ),
 	m_hasParent( parent != NULL  ),
 	m_parent( parent ),
 	m_hadChildren( false ),
@@ -105,17 +106,6 @@ NotePlayHandle::NotePlayHandle( InstrumentTrack* instrumentTrack,
 		m_instrumentTrack->midiNoteOn( *this );
 	}
 
-	if( hasParent() || ! m_instrumentTrack->isArpeggioEnabled() )
-	{
-		const int baseVelocity = m_instrumentTrack->midiPort()->baseVelocity();
-
-		// send MidiNoteOn event
-		m_instrumentTrack->processOutEvent(
-			MidiEvent( MidiNoteOn, midiChannel(), midiKey(), midiVelocity( baseVelocity ) ),
-			MidiTime::fromFrames( offset(), Engine::framesPerTick() ),
-			offset() );
-	}
-
 	if( m_instrumentTrack->instrument()->flags() & Instrument::IsSingleStreamed )
 	{
 		setUsesBuffer( false );
@@ -205,6 +195,21 @@ void NotePlayHandle::play( sampleFrame * _working_buffer )
 	}
 
 	lock();
+
+	if( m_totalFramesPlayed == 0 && !m_hasMidiNote
+		&& ( hasParent() || ! m_instrumentTrack->isArpeggioEnabled() ) )
+	{
+		m_hasMidiNote = true;
+
+		const int baseVelocity = m_instrumentTrack->midiPort()->baseVelocity();
+
+		// send MidiNoteOn event
+		m_instrumentTrack->processOutEvent(
+			MidiEvent( MidiNoteOn, midiChannel(), midiKey(), midiVelocity( baseVelocity ) ),
+			MidiTime::fromFrames( offset(), Engine::framesPerTick() ),
+			offset() );
+	}
+
 	if( m_frequencyNeedsUpdate )
 	{
 		updateFrequency();
@@ -357,8 +362,10 @@ void NotePlayHandle::noteOff( const f_cnt_t _s )
 	m_framesBeforeRelease = _s;
 	m_releaseFramesToDo = qMax<f_cnt_t>( 0, actualReleaseFramesToDo() );
 
-	if( hasParent() || ! m_instrumentTrack->isArpeggioEnabled() )
+	if( m_hasMidiNote )
 	{
+		m_hasMidiNote = false;
+
 		// send MidiNoteOff event
 		m_instrumentTrack->processOutEvent(
 				MidiEvent( MidiNoteOff, midiChannel(), midiKey(), 0 ),
diff --git a/src/core/PeakController.cpp b/src/core/PeakController.cpp
index 9e5e654a6..b2e3bc921 100644
--- a/src/core/PeakController.cpp
+++ b/src/core/PeakController.cpp
@@ -53,8 +53,10 @@ PeakController::PeakController( Model * _parent,
 			this, SLOT( handleDestroyedEffect( ) ) );
 	}
 	connect( Engine::mixer(), SIGNAL( sampleRateChanged() ), this, SLOT( updateCoeffs() ) );
-	connect( m_peakEffect->attackModel(), SIGNAL( dataChanged() ), this, SLOT( updateCoeffs() ) );
-	connect( m_peakEffect->decayModel(), SIGNAL( dataChanged() ), this, SLOT( updateCoeffs() ) );
+	connect( m_peakEffect->attackModel(), SIGNAL( dataChanged() ),
+			this, SLOT( updateCoeffs() ), Qt::DirectConnection );
+	connect( m_peakEffect->decayModel(), SIGNAL( dataChanged() ),
+			this, SLOT( updateCoeffs() ), Qt::DirectConnection );
 	m_coeffNeedsUpdate = true;
 }
 
diff --git a/src/core/PluginIssue.cpp b/src/core/PluginIssue.cpp
new file mode 100644
index 000000000..4a8b2ee5b
--- /dev/null
+++ b/src/core/PluginIssue.cpp
@@ -0,0 +1,72 @@
+/*
+ * PluginIssue.h - PluginIssue class
+ *
+ * Copyright (c) 2019 Johannes Lorenz <j.git$$$lorenz-ho.me, $$$=@>
+ *
+ * This file is part of LMMS - https://lmms.io
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program 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
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program (see COPYING); if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include <QDebug>
+
+#include "PluginIssue.h"
+
+const char *PluginIssue::msgFor(const PluginIssueType &it)
+{
+	switch (it)
+	{
+		case unknownPortFlow:
+			return "unknown port flow for mandatory port";
+		case unknownPortType:
+			return "unknown port type for mandatory port";
+		case tooManyInputChannels:
+			return "too many audio input channels";
+		case tooManyOutputChannels:
+			return "too many audio output channels";
+		case noOutputChannel:
+			return "no audio output channel";
+		case portHasNoDef:
+			return "port is missing default value";
+		case portHasNoMin:
+			return "port is missing min value";
+		case portHasNoMax:
+			return "port is missing max value";
+		case featureNotSupported:
+			return "required feature not supported";
+		case badPortType:
+			return "unsupported port type";
+		case noIssue:
+			return nullptr;
+	}
+	return nullptr;
+}
+
+
+
+
+QDebug operator<<(QDebug stream, const PluginIssue &iss)
+{
+	stream << PluginIssue::msgFor(iss.m_issueType);
+	if (iss.m_info.length())
+	{
+		stream.nospace() << ": " << iss.m_info.c_str();
+	}
+	return stream;
+}
+
+
diff --git a/src/core/Song.cpp b/src/core/Song.cpp
index 2f57b51c3..2809c61ad 100644
--- a/src/core/Song.cpp
+++ b/src/core/Song.cpp
@@ -92,18 +92,18 @@ Song::Song() :
 {
 	for(int i = 0; i < Mode_Count; ++i) m_elapsedMilliSeconds[i] = 0;
 	connect( &m_tempoModel, SIGNAL( dataChanged() ),
-						this, SLOT( setTempo() ) );
+			this, SLOT( setTempo() ), Qt::DirectConnection );
 	connect( &m_tempoModel, SIGNAL( dataUnchanged() ),
-						this, SLOT( setTempo() ) );
+			this, SLOT( setTempo() ), Qt::DirectConnection );
 	connect( &m_timeSigModel, SIGNAL( dataChanged() ),
-					this, SLOT( setTimeSignature() ) );
+			this, SLOT( setTimeSignature() ), Qt::DirectConnection );
 
 
 	connect( Engine::mixer(), SIGNAL( sampleRateChanged() ), this,
 						SLOT( updateFramesPerTick() ) );
 
 	connect( &m_masterVolumeModel, SIGNAL( dataChanged() ),
-			this, SLOT( masterVolumeChanged() ) );
+			this, SLOT( masterVolumeChanged() ), Qt::DirectConnection );
 /*	connect( &m_masterPitchModel, SIGNAL( dataChanged() ),
 			this, SLOT( masterPitchChanged() ) );*/
 
diff --git a/src/core/TempoSyncKnobModel.cpp b/src/core/TempoSyncKnobModel.cpp
index e94c6e424..a85ca2e9f 100644
--- a/src/core/TempoSyncKnobModel.cpp
+++ b/src/core/TempoSyncKnobModel.cpp
@@ -42,7 +42,8 @@ TempoSyncKnobModel::TempoSyncKnobModel( const float _val, const float _min,
 	m_custom( _parent )
 {
 	connect( Engine::getSong(), SIGNAL( tempoChanged( bpm_t ) ),
-			this, SLOT( calculateTempoSyncTime( bpm_t ) ) );
+			this, SLOT( calculateTempoSyncTime( bpm_t ) ),
+			Qt::DirectConnection );
 }
 
 
@@ -154,7 +155,8 @@ void TempoSyncKnobModel::setSyncMode( TempoSyncMode _new_mode )
 		if( _new_mode == SyncCustom )
 		{
 			connect( &m_custom, SIGNAL( dataChanged() ),
-					this, SLOT( updateCustom() ) );
+					this, SLOT( updateCustom() ),
+					Qt::DirectConnection );
 		}
 	}
 	calculateTempoSyncTime( Engine::getSong()->getTempo() );
diff --git a/src/core/Track.cpp b/src/core/Track.cpp
index d08144e47..64c17c9e8 100644
--- a/src/core/Track.cpp
+++ b/src/core/Track.cpp
@@ -328,8 +328,8 @@ TrackContentObjectView::~TrackContentObjectView()
 
 /*! \brief Update a TrackContentObjectView
  *
- *  TCO's get drawn only when needed, 
- *  and when a TCO is updated, 
+ *  TCO's get drawn only when needed,
+ *  and when a TCO is updated,
  *  it needs to be redrawn.
  *
  */
@@ -598,9 +598,9 @@ void TrackContentObjectView::dropEvent( QDropEvent * de )
  */
 void TrackContentObjectView::leaveEvent( QEvent * e )
 {
-	while( QApplication::overrideCursor() != NULL )
+	if( cursor().shape() != Qt::BitmapCursor )
 	{
-		QApplication::restoreOverrideCursor();
+		setCursor( QCursor( embed::getIconPixmap( "hand" ), 3, 3 ) );
 	}
 	if( e != NULL )
 	{
@@ -746,20 +746,17 @@ void TrackContentObjectView::mousePressEvent( QMouseEvent * me )
 						&& !m_tco->getAutoResize() )
 				{
 					m_action = ResizeLeft;
-					QCursor c( Qt::SizeHorCursor );
-					QApplication::setOverrideCursor( c );
+					setCursor( Qt::SizeHorCursor );
 				}
 				else if( me->x() < width() - RESIZE_GRIP_WIDTH )
 				{
 					m_action = Move;
-					QCursor c( Qt::SizeAllCursor );
-					QApplication::setOverrideCursor( c );
+					setCursor( Qt::SizeAllCursor );
 				}
 				else if( !m_tco->getAutoResize() )
 				{
 					m_action = Resize;
-					QCursor c( Qt::SizeHorCursor );
-					QApplication::setOverrideCursor( c );
+					setCursor( Qt::SizeHorCursor );
 				}
 
 				if( m_action == Move )
@@ -1007,17 +1004,7 @@ void TrackContentObjectView::mouseMoveEvent( QMouseEvent * me )
 		if( ( me->x() > width() - RESIZE_GRIP_WIDTH && !me->buttons() && !m_tco->getAutoResize() )
 		||  ( me->x() < RESIZE_GRIP_WIDTH && !me->buttons() && sTco && !m_tco->getAutoResize() ) )
 		{
-			if( QApplication::overrideCursor() != NULL &&
-				QApplication::overrideCursor()->shape() !=
-							Qt::SizeHorCursor )
-			{
-				while( QApplication::overrideCursor() != NULL )
-				{
-					QApplication::restoreOverrideCursor();
-				}
-			}
-			QCursor c( Qt::SizeHorCursor );
-			QApplication::setOverrideCursor( c );
+			setCursor( Qt::SizeHorCursor );
 		}
 		else
 		{
@@ -1194,7 +1181,7 @@ void TrackContentWidget::updateBackground()
 
 	// draw lines
 	// vertical lines
-	pmp.setPen( QPen( gridColor(), 1 ) );	
+	pmp.setPen( QPen( gridColor(), 1 ) );
 	for( float x = 0; x < w * 2; x += ppt )
 	{
 		pmp.drawLine( QLineF( x, 0.0, x, h ) );
@@ -1205,9 +1192,9 @@ void TrackContentWidget::updateBackground()
 	{
 		pmp.drawLine( QLineF( x, 0.0, x, h ) );
 	}
-	
+
 	// horizontal line
-	pmp.setPen( QPen( gridColor(), 1 ) );	
+	pmp.setPen( QPen( gridColor(), 1 ) );
 	pmp.drawLine( 0, h-1, w*2, h-1 );
 
 	pmp.end();
@@ -1390,7 +1377,7 @@ MidiTime TrackContentWidget::getPosition( int mouseX )
  */
 void TrackContentWidget::dragEnterEvent( QDragEnterEvent * dee )
 {
-	MidiTime tcoPos = MidiTime( getPosition( dee->pos().x() ).getTact(), 0 );
+	MidiTime tcoPos = getPosition( dee->pos().x() );
 	if( canPasteSelection( tcoPos, dee ) == false )
 	{
 		dee->ignore();
@@ -1928,7 +1915,7 @@ void TrackOperationsWidget::updateMenu()
 	toMenu->addAction( embed::getIconPixmap( "cancel", 16, 16 ),
 						tr( "Remove this track" ),
 						this, SLOT( removeTrack() ) );
-	
+
 	if( ! m_trackView->trackContainerView()->fixedTCOs() )
 	{
 		toMenu->addAction( tr( "Clear this track" ), this, SLOT( clearTrack() ) );
@@ -2624,7 +2611,7 @@ TrackView::TrackView( Track * track, TrackContainerView * tcv ) :
 			&m_trackContentWidget, SLOT( update() ) );
 
 	connect( &m_track->m_soloModel, SIGNAL( dataChanged() ),
-			m_track, SLOT( toggleSolo() ) );
+			m_track, SLOT( toggleSolo() ), Qt::DirectConnection );
 	// create views for already existing TCOs
 	for( Track::tcoVector::iterator it =
 					m_track->m_trackContentObjects.begin();
@@ -2871,12 +2858,12 @@ void TrackView::mouseMoveEvent( QMouseEvent * me )
 	else if( m_action == MoveTrack )
 	{
 		// look which track-widget the mouse-cursor is over
-		const int yPos = 
+		const int yPos =
 			m_trackContainerView->contentWidget()->mapFromGlobal( me->globalPos() ).y();
 		const TrackView * trackAtY = m_trackContainerView->trackViewAt( yPos );
 
-// debug code
-//			qDebug( "y position %d", yPos );
+		// debug code
+		//	qDebug( "y position %d", yPos );
 
 		// a track-widget not equal to ourself?
 		if( trackAtY != NULL && trackAtY != this )
diff --git a/src/core/midi/MidiAlsaSeq.cpp b/src/core/midi/MidiAlsaSeq.cpp
index be1e623de..e420ebc08 100644
--- a/src/core/midi/MidiAlsaSeq.cpp
+++ b/src/core/midi/MidiAlsaSeq.cpp
@@ -100,7 +100,7 @@ MidiAlsaSeq::MidiAlsaSeq() :
 	snd_seq_start_queue( m_seqHandle, m_queueID, NULL );
 	changeQueueTempo( Engine::getSong()->getTempo() );
 	connect( Engine::getSong(), SIGNAL( tempoChanged( bpm_t ) ),
-			this, SLOT( changeQueueTempo( bpm_t ) ) );
+			this, SLOT( changeQueueTempo( bpm_t ) ), Qt::DirectConnection );
 
 	// initial list-update
 	updatePortList();
diff --git a/src/core/midi/MidiPort.cpp b/src/core/midi/MidiPort.cpp
index 9e3cdb13d..52e0a5223 100644
--- a/src/core/midi/MidiPort.cpp
+++ b/src/core/midi/MidiPort.cpp
@@ -63,9 +63,12 @@ MidiPort::MidiPort( const QString& name,
 	m_readableModel.setValue( m_mode == Input || m_mode == Duplex );
 	m_writableModel.setValue( m_mode == Output || m_mode == Duplex );
 
-	connect( &m_readableModel, SIGNAL( dataChanged() ), this, SLOT( updateMidiPortMode() ) );
-	connect( &m_writableModel, SIGNAL( dataChanged() ), this, SLOT( updateMidiPortMode() ) );
-	connect( &m_outputProgramModel, SIGNAL( dataChanged() ), this, SLOT( updateOutputProgram() ) );
+	connect( &m_readableModel, SIGNAL( dataChanged() ),
+			this, SLOT( updateMidiPortMode() ), Qt::DirectConnection );
+	connect( &m_writableModel, SIGNAL( dataChanged() ),
+			this, SLOT( updateMidiPortMode() ), Qt::DirectConnection );
+	connect( &m_outputProgramModel, SIGNAL( dataChanged() ),
+			this, SLOT( updateOutputProgram() ), Qt::DirectConnection );
 
 
 	// when using with non-raw-clients we can provide buttons showing
diff --git a/src/gui/FileBrowser.cpp b/src/gui/FileBrowser.cpp
index 4311e4e05..7eeb87ed2 100644
--- a/src/gui/FileBrowser.cpp
+++ b/src/gui/FileBrowser.cpp
@@ -163,6 +163,7 @@ bool FileBrowser::filterItems( const QString & filter, QTreeWidgetItem * item )
 
 void FileBrowser::reloadTree( void )
 {
+	QList<QString> expandedDirs = m_fileBrowserTreeWidget->expandedDirs();
 	const QString text = m_filterEdit->text();
 	m_filterEdit->clear();
 	m_fileBrowserTreeWidget->clear();
@@ -171,17 +172,17 @@ void FileBrowser::reloadTree( void )
 	{
 		addItems( *it );
 	}
-	expandItems();
+	expandItems(NULL, expandedDirs);
 	m_filterEdit->setText( text );
 	filterItems( text );
 }
 
 
 
-void FileBrowser::expandItems( QTreeWidgetItem * item )
+void FileBrowser::expandItems( QTreeWidgetItem * item, QList<QString> expandedDirs )
 {
 	int numChildren = item ? item->childCount() : m_fileBrowserTreeWidget->topLevelItemCount();
-	for( int i = 0; i < numChildren; ++i )
+	for (int i = 0; i < numChildren; ++i)
 	{
 		QTreeWidgetItem * it = item ? item->child( i ) : m_fileBrowserTreeWidget->topLevelItem(i);
 		if ( m_recurse )
@@ -189,14 +190,15 @@ void FileBrowser::expandItems( QTreeWidgetItem * item )
 			it->setExpanded( true );
 		}
 		Directory *d = dynamic_cast<Directory *> ( it );
-		if( d )
+		if (d)
 		{
 			d->update();
-			d->setExpanded( false );
+			bool expand = expandedDirs.contains( d->fullName() );
+			d->setExpanded( expand );
 		}
-		if( m_recurse && it->childCount() )
+		if (m_recurse && it->childCount())
 		{
-			expandItems(it);
+			expandItems(it, expandedDirs);
 		}
 	}
 }
@@ -326,6 +328,30 @@ FileBrowserTreeWidget::FileBrowserTreeWidget(QWidget * parent ) :
 
 }
 
+QList<QString> FileBrowserTreeWidget::expandedDirs( QTreeWidgetItem * item ) const
+{
+	int numChildren = item ? item->childCount() : topLevelItemCount();
+	QList<QString> dirs;
+	for (int i = 0; i < numChildren; ++i)
+	{
+		QTreeWidgetItem * it  = item ? item->child(i) : topLevelItem(i);
+
+		// Add expanded top level directories.
+		if (it->isExpanded() && (it->type() == TypeDirectoryItem))
+		{
+			Directory *d = static_cast<Directory *> ( it );
+			dirs.append( d->fullName() );
+		}
+
+		// Add expanded child directories (recurse).
+		if (it->childCount())
+		{
+			dirs.append( expandedDirs( it ) );
+		}
+	}
+	return dirs;
+}
+
 void FileBrowserTreeWidget::contextMenuEvent(QContextMenuEvent * e )
 {
 	FileItem * f = dynamic_cast<FileItem *>( itemAt( e->pos() ) );
diff --git a/src/gui/FxMixerView.cpp b/src/gui/FxMixerView.cpp
index 0a6a54866..90cd1dbf3 100644
--- a/src/gui/FxMixerView.cpp
+++ b/src/gui/FxMixerView.cpp
@@ -313,7 +313,7 @@ FxMixerView::FxChannelView::FxChannelView(QWidget * _parent, FxMixerView * _mv,
 	m_soloBtn->setCheckable( true );
 	m_soloBtn->move( 9,  m_fader->y()-21);
 	connect(&fxChannel->m_soloModel, SIGNAL( dataChanged() ),
-			_mv, SLOT ( toggledSolo() ) );
+			_mv, SLOT ( toggledSolo() ), Qt::DirectConnection );
 	ToolTip::add( m_soloBtn, tr( "Solo FX channel" ) );
 
 	// Create EffectRack for the channel
diff --git a/src/gui/InstrumentView.cpp b/src/gui/InstrumentView.cpp
index 93e153f6f..cf19bbbe1 100644
--- a/src/gui/InstrumentView.cpp
+++ b/src/gui/InstrumentView.cpp
@@ -34,7 +34,6 @@ InstrumentView::InstrumentView( Instrument * _Instrument, QWidget * _parent ) :
 	PluginView( _Instrument, _parent )
 {
 	setModel( _Instrument );
-	setFixedSize( 250, 250 );
 	setAttribute( Qt::WA_DeleteOnClose, true );
 }
 
diff --git a/src/gui/editors/PianoRoll.cpp b/src/gui/editors/PianoRoll.cpp
index 76b2d04f1..a3ff9c5fd 100644
--- a/src/gui/editors/PianoRoll.cpp
+++ b/src/gui/editors/PianoRoll.cpp
@@ -1007,6 +1007,9 @@ void PianoRoll::drawDetuningInfo( QPainter & _p, const Note * _n, int _x,
 {
 	int middle_y = _y + KEY_LINE_HEIGHT / 2;
 	_p.setPen( noteColor() );
+	_p.setClipRect(WHITE_KEY_WIDTH, PR_TOP_MARGIN,
+		width() - WHITE_KEY_WIDTH,
+		keyAreaBottom() - PR_TOP_MARGIN);
 
 	int old_x = 0;
 	int old_y = 0;
@@ -1188,9 +1191,11 @@ void PianoRoll::keyPressEvent(QKeyEvent* ke)
 	{
 		const int key_num = PianoView::getKeyFromKeyEvent( ke ) + ( DefaultOctave - 1 ) * KeysPerOctave;
 
-		if(! ke->isAutoRepeat() && key_num > -1)
+		if (!ke->isAutoRepeat() && key_num > -1)
 		{
-			m_pattern->instrumentTrack()->pianoModel()->handleKeyPress( key_num );
+			m_pattern->instrumentTrack()->pianoModel()->handleKeyPress(key_num);
+			//  if a chord is set, play all chord notes (simulate click on all):
+			playChordNotes(key_num);
 			ke->accept();
 		}
 	}
@@ -1388,10 +1393,11 @@ void PianoRoll::keyReleaseEvent(QKeyEvent* ke )
 	if( hasValidPattern() && ke->modifiers() == Qt::NoModifier )
 	{
 		const int key_num = PianoView::getKeyFromKeyEvent( ke ) + ( DefaultOctave - 1 ) * KeysPerOctave;
-
-		if( ! ke->isAutoRepeat() && key_num > -1 )
+		if (!ke->isAutoRepeat() && key_num > -1)
 		{
-			m_pattern->instrumentTrack()->pianoModel()->handleKeyRelease( key_num );
+			m_pattern->instrumentTrack()->pianoModel()->handleKeyRelease(key_num);
+			// if a chord is set, simulate click release on all chord notes
+			pauseChordNotes(key_num);
 			ke->accept();
 		}
 	}
@@ -1836,7 +1842,9 @@ void PianoRoll::mousePressEvent(QMouseEvent * me )
 			{
 				// left click - play the note
 				int v = ( (float) x ) / ( (float) WHITE_KEY_WIDTH ) * MidiDefaultVelocity;
-				m_pattern->instrumentTrack()->pianoModel()->handleKeyPress( key_num, v );
+				m_pattern->instrumentTrack()->pianoModel()->handleKeyPress(key_num, v);
+				// if a chord is set, play the chords notes as well:
+				playChordNotes(key_num, v);
 			}
 		}
 		else
@@ -1939,7 +1947,10 @@ void PianoRoll::testPlayNote( Note * n )
 
 		const int baseVelocity = m_pattern->instrumentTrack()->midiPort()->baseVelocity();
 
-		m_pattern->instrumentTrack()->pianoModel()->handleKeyPress( n->key(), n->midiVelocity( baseVelocity ) );
+		m_pattern->instrumentTrack()->pianoModel()->handleKeyPress(n->key(), n->midiVelocity(baseVelocity));
+
+		// if a chord is set, play the chords notes as well:
+		playChordNotes(n->key(), n->midiVelocity(baseVelocity));
 
 		MidiEvent event( MidiMetaEvent, -1, n->key(), panningToMidi( n->getPanning() ) );
 
@@ -1962,6 +1973,9 @@ void PianoRoll::pauseTestNotes( bool pause )
 			{
 				// stop note
 				m_pattern->instrumentTrack()->pianoModel()->handleKeyRelease( note->key() );
+
+				// if a chord was set, stop the chords notes as well:
+				pauseChordNotes(note->key());
 			}
 			else
 			{
@@ -1973,19 +1987,56 @@ void PianoRoll::pauseTestNotes( bool pause )
 	}
 }
 
+void PianoRoll::playChordNotes(int key, int velocity)
+{
+	// if a chord is set, play the chords notes beside the base note.
+	Piano *pianoModel = m_pattern->instrumentTrack()->pianoModel();
+	const InstrumentFunctionNoteStacking::Chord & chord =
+			InstrumentFunctionNoteStacking::ChordTable::getInstance().getChordByName(
+				m_chordModel.currentText());
+	if (!chord.isEmpty())
+	{
+		for (int i = 1; i < chord.size(); ++i)
+		{
+			pianoModel->handleKeyPress(key + chord[i], velocity);
+		}
+	}
+}
+
+void PianoRoll::pauseChordNotes(int key)
+{
+	// if a chord was set, stop the chords notes beside the base note.
+	Piano *pianoModel = m_pattern->instrumentTrack()->pianoModel();
+	const InstrumentFunctionNoteStacking::Chord & chord =
+			InstrumentFunctionNoteStacking::ChordTable::getInstance().getChordByName(
+				m_chordModel.currentText());
+	if (!chord.isEmpty())
+	{
+		for (int i = 1; i < chord.size(); ++i)
+		{
+			pianoModel->handleKeyRelease(key + chord[i]);
+		}
+	}
+}
+
 
 
 
 void PianoRoll::testPlayKey( int key, int velocity, int pan )
 {
+	Piano *pianoModel = m_pattern->instrumentTrack()->pianoModel();
 	// turn off old key
-	m_pattern->instrumentTrack()->pianoModel()->handleKeyRelease( m_lastKey );
+	pianoModel->handleKeyRelease( m_lastKey );
+	// if a chord was set, stop the chords notes as well
+	pauseChordNotes(m_lastKey);
 
 	// remember which one we're playing
 	m_lastKey = key;
 
 	// play new key
-	m_pattern->instrumentTrack()->pianoModel()->handleKeyPress( key, velocity );
+	pianoModel->handleKeyPress( key, velocity );
+	// and if a chord is set, play chord notes:
+	playChordNotes(key, velocity);
 }
 
 
@@ -2115,6 +2166,7 @@ void PianoRoll::mouseReleaseEvent( QMouseEvent * me )
 			{
 				m_pattern->instrumentTrack()->pianoModel()->
 						handleKeyRelease( note->key() );
+				pauseChordNotes(note->key());
 				note->setIsPlaying( false );
 			}
 		}
@@ -2122,6 +2174,7 @@ void PianoRoll::mouseReleaseEvent( QMouseEvent * me )
 		// stop playing keys that we let go of
 		m_pattern->instrumentTrack()->pianoModel()->
 						handleKeyRelease( m_lastKey );
+		pauseChordNotes(m_lastKey);
 	}
 
 	m_currentNote = NULL;
@@ -2309,6 +2362,7 @@ void PianoRoll::mouseMoveEvent( QMouseEvent * me )
 				{
 					// mouse not over this note, stop playing it.
 					m_pattern->instrumentTrack()->pianoModel()->handleKeyRelease( n->key() );
+					pauseChordNotes(n->key());
 
 					n->setIsPlaying( false );
 				}
@@ -3255,6 +3309,9 @@ void PianoRoll::paintEvent(QPaintEvent * pe )
 				drawDetuningInfo( p, note,
 					x + WHITE_KEY_WIDTH,
 					y_base - key * KEY_LINE_HEIGHT );
+				p.setClipRect(WHITE_KEY_WIDTH, PR_TOP_MARGIN,
+					width() - WHITE_KEY_WIDTH,
+					height() - PR_TOP_MARGIN);
 			}
 		}
 
diff --git a/src/gui/widgets/Graph.cpp b/src/gui/widgets/Graph.cpp
index f93ed523c..4710089dd 100644
--- a/src/gui/widgets/Graph.cpp
+++ b/src/gui/widgets/Graph.cpp
@@ -635,13 +635,14 @@ void graphModel::smoothNonCyclic()
 	emit samplesChanged(0, length()-1);
 }
 
-//makes a cyclic convolution.
-void graphModel::convolve(const float *convolution, const int convolutionLength, const int centerOffset)
+void graphModel::convolve(const float *convolution,
+	const int convolutionLength, const int centerOffset)
 {
 	// store values in temporary array
 	QVector<float> temp = m_samples;
 	const int graphLength = length();
 	float sum;
+	// make a cyclic convolution
 	for ( int i = 0; i <  graphLength; i++ )
 	{
 		sum = 0;
diff --git a/src/gui/widgets/TabWidget.cpp b/src/gui/widgets/TabWidget.cpp
index f06710098..9bdbec2e0 100644
--- a/src/gui/widgets/TabWidget.cpp
+++ b/src/gui/widgets/TabWidget.cpp
@@ -34,8 +34,10 @@
 #include "gui_templates.h"
 #include "embed.h"
 
-TabWidget::TabWidget( const QString & caption, QWidget * parent, bool usePixmap ) :
+TabWidget::TabWidget(const QString & caption, QWidget * parent, bool usePixmap,
+					 bool resizable) :
 	QWidget( parent ),
+	m_resizable( resizable ),
 	m_activeTab( 0 ),
 	m_caption( caption ),
 	m_usePixmap( usePixmap ),
@@ -81,7 +83,10 @@ void TabWidget::addTab( QWidget * w, const QString & name, const char *pixmap, i
 	m_widgets[idx] = d;
 
 	// Position tab's window
-	w->setFixedSize( width() - 4, height() - m_tabbarHeight );
+	if (!m_resizable)
+	{
+		w->setFixedSize( width() - 4, height() - m_tabbarHeight );
+	}
 	w->move( 2, m_tabbarHeight - 1 );
 	w->hide();
 
@@ -189,17 +194,19 @@ void TabWidget::mousePressEvent( QMouseEvent * me )
 
 void TabWidget::resizeEvent( QResizeEvent * )
 {
-	for( widgetStack::iterator it = m_widgets.begin();
-						it != m_widgets.end(); ++it )
+	if (!m_resizable)
 	{
-		( *it ).w->setFixedSize( width() - 4, height() - m_tabbarHeight );
+		for ( widgetStack::iterator it = m_widgets.begin();
+							it != m_widgets.end(); ++it )
+		{
+			( *it ).w->setFixedSize( width() - 4, height() - m_tabbarHeight );
+		}
 	}
 }
 
 
 
 
-
 void TabWidget::paintEvent( QPaintEvent * pe )
 {
 	QPainter p( this );
@@ -284,7 +291,7 @@ void TabWidget::wheelEvent( QWheelEvent * we )
 	if( we->y() > m_tabheight )
 	{
 		return;
-  }
+	}
 
 	we->accept();
 	int dir = ( we->delta() < 0 ) ? 1 : -1;
@@ -300,6 +307,32 @@ void TabWidget::wheelEvent( QWheelEvent * we )
 	setActiveTab( tab );
 }
 
+
+
+
+// Let parent widgets know how much space this tab widget needs
+QSize TabWidget::minimumSizeHint() const
+{
+	if (m_resizable)
+	{
+		int maxWidth = 0, maxHeight = 0;
+		for ( widgetStack::const_iterator it = m_widgets.begin();
+							it != m_widgets.end(); ++it )
+		{
+			maxWidth = std::max(maxWidth, it->w->width());
+			maxHeight = std::max(maxHeight, it->w->height());
+		}
+		// "-1" :
+		// in "addTab", under "Position tab's window", the widget is
+		// moved up by 1 pixel
+		return QSize(maxWidth + 4, maxHeight + m_tabbarHeight - 1);
+	}
+	else { return QWidget::minimumSizeHint(); }
+}
+
+
+
+
 // Return the color to be used to draw a TabWidget's title text (if any)
 QColor TabWidget::tabTitleText() const
 {
diff --git a/src/tracks/BBTrack.cpp b/src/tracks/BBTrack.cpp
index c37c1466f..205a22087 100644
--- a/src/tracks/BBTrack.cpp
+++ b/src/tracks/BBTrack.cpp
@@ -635,5 +635,6 @@ bool BBTrackView::close()
 void BBTrackView::clickedTrackLabel()
 {
 	Engine::getBBTrackContainer()->setCurrentBB( m_bbTrack->index() );
-	gui->getBBEditor()->show();
+	gui->getBBEditor()->parentWidget()->show();
+	gui->getBBEditor()->setFocus( Qt::ActiveWindowFocusReason );
 }
diff --git a/src/tracks/InstrumentTrack.cpp b/src/tracks/InstrumentTrack.cpp
index 0142952cf..6c95f3c9a 100644
--- a/src/tracks/InstrumentTrack.cpp
+++ b/src/tracks/InstrumentTrack.cpp
@@ -1298,7 +1298,7 @@ InstrumentTrackWindow::InstrumentTrackWindow( InstrumentTrackView * _itv ) :
 				this, SLOT( textChanged( const QString & ) ) );
 
 	m_nameLineEdit->setSizePolicy(QSizePolicy(QSizePolicy::Expanding, QSizePolicy::Preferred));
-	nameAndChangeTrackLayout->addWidget(m_nameLineEdit);
+	nameAndChangeTrackLayout->addWidget(m_nameLineEdit, 1);
 
 
 	// set up left/right arrows for changing instrument
@@ -1410,8 +1410,11 @@ InstrumentTrackWindow::InstrumentTrackWindow( InstrumentTrackView * _itv ) :
 	generalSettingsLayout->addLayout( basicControlsLayout );
 
 
-	m_tabWidget = new TabWidget( "", this, true );
-	m_tabWidget->setFixedHeight( INSTRUMENT_HEIGHT + GRAPHIC_TAB_HEIGHT - 4 );
+	m_tabWidget = new TabWidget( "", this, true, true );
+	// "-1" :
+	// in "TabWidget::addTab", under "Position tab's window", the widget is
+	// moved up by 1 pixel
+	m_tabWidget->setMinimumHeight( INSTRUMENT_HEIGHT + GRAPHIC_TAB_HEIGHT - 4 - 1 );
 
 
 	// create tab-widgets
@@ -1443,24 +1446,27 @@ InstrumentTrackWindow::InstrumentTrackWindow( InstrumentTrackView * _itv ) :
 	m_tabWidget->addTab( m_effectView, tr( "Effects" ), "fx_tab", 3 );
 	m_tabWidget->addTab( m_midiView, tr( "MIDI" ), "midi_tab", 4 );
 	m_tabWidget->addTab( m_miscView, tr( "Miscellaneous" ), "misc_tab", 5 );
+	adjustTabSize(m_ssView);
+	adjustTabSize(instrumentFunctions);
+	adjustTabSize(m_effectView);
+	adjustTabSize(m_midiView);
+	adjustTabSize(m_miscView);
 
 	// setup piano-widget
 	m_pianoView = new PianoView( this );
-	m_pianoView->setFixedSize( INSTRUMENT_WIDTH, PIANO_HEIGHT );
+	m_pianoView->setMinimumHeight( PIANO_HEIGHT );
+	m_pianoView->setMaximumHeight( PIANO_HEIGHT );
 
 	vlayout->addWidget( generalSettingsWidget );
-	vlayout->addWidget( m_tabWidget );
+	vlayout->addWidget( m_tabWidget, 1 );
 	vlayout->addWidget( m_pianoView );
-
-
 	setModel( _itv->model() );
 
 	updateInstrumentView();
 
-	setFixedWidth( INSTRUMENT_WIDTH );
 	resize( sizeHint() );
 
-	QMdiSubWindow * subWin = gui->mainWindow()->addWindowedWidget( this );
+	QMdiSubWindow* subWin = gui->mainWindow()->addWindowedWidget( this );
 	Qt::WindowFlags flags = subWin->windowFlags();
 	flags |= Qt::MSWindowsFixedSizeDialogHint;
 	flags &= ~Qt::WindowMaximizeButtonHint;
@@ -1473,7 +1479,7 @@ InstrumentTrackWindow::InstrumentTrackWindow( InstrumentTrackView * _itv ) :
 	systemMenu->actions().at( 4 )->setVisible( false ); // Maximize
 
 	subWin->setWindowIcon( embed::getIconPixmap( "instrument_track" ) );
-	subWin->setFixedSize( subWin->size() );
+	subWin->setMinimumSize( subWin->size() );
 	subWin->hide();
 }
 
@@ -1624,6 +1630,7 @@ void InstrumentTrackWindow::updateInstrumentView()
 		modelChanged(); 		// Get the instrument window to refresh
 		m_track->dataChanged(); // Get the text on the trackButton to change
 
+		adjustTabSize(m_instrumentView);
 		m_pianoView->setVisible(m_track->m_instrument->hasNoteInput());
 	}
 }
@@ -1819,6 +1826,7 @@ void InstrumentTrackWindow::viewInstrumentInDirection(int d)
 		// get the instrument window to refresh
 		modelChanged();
 	}
+	Q_ASSERT(bringToFront);
 	bringToFront->getInstrumentTrackWindow()->setFocus();
 }
 
@@ -1831,4 +1839,12 @@ void InstrumentTrackWindow::viewPrevInstrument()
 	viewInstrumentInDirection(-1);
 }
 
+void InstrumentTrackWindow::adjustTabSize(QWidget *w)
+{
+	// "-1" :
+	// in "TabWidget::addTab", under "Position tab's window", the widget is
+	// moved up by 1 pixel
+	w->setMinimumSize(INSTRUMENT_WIDTH - 4, INSTRUMENT_HEIGHT - 4 - 1);
+}
+
 #include "InstrumentTrack.moc"
diff --git a/src/tracks/SampleTrack.cpp b/src/tracks/SampleTrack.cpp
index c965af140..959d6389e 100644
--- a/src/tracks/SampleTrack.cpp
+++ b/src/tracks/SampleTrack.cpp
@@ -65,7 +65,7 @@ SampleTCO::SampleTCO( Track * _track ) :
 	// we need to receive bpm-change-events, because then we have to
 	// change length of this TCO
 	connect( Engine::getSong(), SIGNAL( tempoChanged( bpm_t ) ),
-					this, SLOT( updateLength() ) );
+					this, SLOT( updateLength() ), Qt::DirectConnection );
 	connect( Engine::getSong(), SIGNAL( timeSignatureChanged( int,int ) ),
 					this, SLOT( updateLength() ) );
 
@@ -110,7 +110,7 @@ SampleTCO::SampleTCO( Track * _track ) :
 SampleTCO::~SampleTCO()
 {
 	SampleTrack * sampletrack = dynamic_cast<SampleTrack*>( getTrack() );
-	if( sampletrack)
+	if ( sampletrack )
 	{
 		sampletrack->updateTcos();
 	}
@@ -122,10 +122,7 @@ SampleTCO::~SampleTCO()
 
 void SampleTCO::changeLength( const MidiTime & _length )
 {
-	float nom = Engine::getSong()->getTimeSigModel().getNumerator();
-	float den = Engine::getSong()->getTimeSigModel().getDenominator();
-	int ticksPerTact = DefaultTicksPerTact * ( nom / den );
-	TrackContentObject::changeLength( qMax( static_cast<int>( _length ), ticksPerTact ) );
+	TrackContentObject::changeLength( qMax( static_cast<int>( _length ), 1 ) );
 }
 
 
@@ -151,9 +148,21 @@ void SampleTCO::setSampleBuffer( SampleBuffer* sb )
 
 void SampleTCO::setSampleFile( const QString & _sf )
 {
-	m_sampleBuffer->setAudioFile( _sf );
+	int length;
+	if ( _sf.isEmpty() )
+	{	//When creating an empty sample pattern make it a bar long
+		float nom = Engine::getSong()->getTimeSigModel().getNumerator();
+		float den = Engine::getSong()->getTimeSigModel().getDenominator();
+		length = DefaultTicksPerTact * ( nom / den );
+	}
+	else
+	{	//Otherwise set it to the sample's length
+		m_sampleBuffer->setAudioFile( _sf );
+		length = sampleLength();
+	}
+	changeLength(length);
+
 	setStartTimeOffset( 0 );
-	changeLength( (int) ( m_sampleBuffer->frames() / Engine::framesPerTick() ) );
 
 	emit sampleChanged();
 	emit playbackPositionChanged();
@@ -440,8 +449,15 @@ void SampleTCOView::mouseReleaseEvent(QMouseEvent *_me)
 void SampleTCOView::mouseDoubleClickEvent( QMouseEvent * )
 {
 	QString af = m_tco->m_sampleBuffer->openAudioFile();
-	if( af != "" && af != m_tco->m_sampleBuffer->audioFile() )
-	{
+
+	if ( af.isEmpty() ) {} //Don't do anything if no file is loaded
+	else if ( af == m_tco->m_sampleBuffer->audioFile() )
+	{	//Instead of reloading the existing file, just reset the size
+		int length = (int) ( m_tco->m_sampleBuffer->frames() / Engine::framesPerTick() );
+		m_tco->changeLength(length);
+	}
+	else
+	{	//Otherwise load the new file as ususal
 		m_tco->setSampleFile( af );
 		Engine::getSong()->setModified();
 	}
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index c39f8e56e..ddebe116c 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -14,6 +14,7 @@ ADD_EXECUTABLE(tests
 	QTestSuite
 	$<TARGET_OBJECTS:lmmsobjs>
 
+	src/core/AutomatableModelTest.cpp
 	src/core/ProjectVersionTest.cpp
 	src/core/RelativePathsTest.cpp
 
diff --git a/tests/src/core/AutomatableModelTest.cpp b/tests/src/core/AutomatableModelTest.cpp
new file mode 100644
index 000000000..116f95e60
--- /dev/null
+++ b/tests/src/core/AutomatableModelTest.cpp
@@ -0,0 +1,55 @@
+/*
+ * AutomatableModelTest.cpp
+ *
+ * Copyright (c) 2019-2019 Johannes Lorenz <j.git$$$lorenz-ho.me, $$$=@>
+ *
+ * This file is part of LMMS - https://lmms.io
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program 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
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program (see COPYING); if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include "QTestSuite.h"
+
+#include "AutomatableModel.h"
+#include "ComboBoxModel.h"
+
+class AutomatableModelTest : QTestSuite
+{
+	Q_OBJECT
+
+private slots:
+	//! Test that upcast and exact casts work,
+	//! but no downcast or any other casts
+	void CastTests()
+	{
+		ComboBoxModel comboModel;
+		AutomatableModel* amPtr = &comboModel;
+		QVERIFY(nullptr == amPtr->dynamicCast<FloatModel>()); // not a parent class
+		QCOMPARE(&comboModel, amPtr->dynamicCast<AutomatableModel>()); // parent class
+		QCOMPARE(&comboModel, amPtr->dynamicCast<IntModel>()); // parent class
+		QCOMPARE(&comboModel, amPtr->dynamicCast<ComboBoxModel>()); // same class
+
+		IntModel intModel;
+		IntModel* imPtr = &intModel;
+		QVERIFY(nullptr == imPtr->dynamicCast<FloatModel>()); // not a parent class
+		QCOMPARE(&intModel, imPtr->dynamicCast<AutomatableModel>()); // parent class
+		QCOMPARE(&intModel, imPtr->dynamicCast<IntModel>()); // same class
+		QVERIFY(nullptr == imPtr->dynamicCast<ComboBoxModel>()); // child class
+	}
+} AutomatableModelTests;
+
+#include "AutomatableModelTest.moc"