Support clear in the timeline controls.

Avoid duplicates item when loading a project.

src/GUI/Timeline.cpp

@@ -74,6 +74,7 @@ Timeline::Timeline( WorkflowRenderer* renderer, QWidget *parent ) :
     connect( m_mainWorkflow, SIGNAL( clipMoved(QUuid, uint, qint64,MainWorkflow::TrackType ) ), this, SLOT( actionMoveClip(QUuid,uint,qint64,MainWorkflow::TrackType ) ) );
     connect( m_mainWorkflow, SIGNAL( clipRemoved(Clip*,uint,MainWorkflow::TrackType ) ), this, SLOT( actionRemoveClip(Clip*,uint,MainWorkflow::TrackType )) );
     connect( m_mainWorkflow, SIGNAL( cleared() ), tracksView(), SLOT( clear() ) );
+    connect( m_mainWorkflow, SIGNAL( cleared() ), m_tracksControls, SLOT( clear() ) );
 
     connect( m_tracksView, SIGNAL( videoTrackAdded(GraphicsTrack*) ),
              m_tracksControls, SLOT( addVideoTrack(GraphicsTrack*) ) );

src/GUI/TracksControls.cpp

@@ -41,11 +41,11 @@ TracksControls::TracksControls( QWidget* parent )
     m_layout->setContentsMargins( 0, 0, 0, 0 );
     m_layout->setSpacing( 0 );
 
-    QWidget* separator = new QWidget;
-    separator->setSizePolicy( QSizePolicy::Minimum, QSizePolicy::Fixed );
-    separator->setMinimumHeight( 20 );
-    separator->setMaximumHeight( 20 );
-    m_layout->addWidget( separator );
+    m_separator = new QWidget;
+    m_separator->setSizePolicy( QSizePolicy::Minimum, QSizePolicy::Fixed );
+    m_separator->setMinimumHeight( 20 );
+    m_separator->setMaximumHeight( 20 );
+    m_layout->addWidget( m_separator );
 
     m_centralWidget->setLayout( m_layout );
     setWidget( m_centralWidget );
@@ -68,3 +68,16 @@ void TracksControls::addAudioTrack( GraphicsTrack* track )
     item->setContentsMargins( 0, 0, 0, 0 );
     m_layout->insertWidget( -1, item );
 }
+
+void TracksControls::clear()
+{
+    m_layout->removeWidget( m_separator );
+    QLayoutItem* child;
+    while ( ( child = m_layout->takeAt( 0 ) ) != 0 )
+    {
+        if ( child->widget() )
+            delete child->widget();
+        delete child;
+    }
+    m_layout->addWidget( m_separator );
+}

src/GUI/TracksControls.h

@@ -37,9 +37,11 @@ public:
 public slots:
     void addVideoTrack( GraphicsTrack* track );
     void addAudioTrack( GraphicsTrack* track );
+    void clear();
 
 private:
     QWidget* m_centralWidget;
+    QWidget* m_separator;
     QVBoxLayout* m_layout;
 };