Fix 'pausing does move the slider to 0'.

modules/gui/qt4/components/interface_widgets.cpp

@@ -965,7 +965,7 @@ void ControlsWidget::enableInput( bool enable )
 {
     slowerButton->setEnabled( enable );
     slider->setEnabled( enable );
-    slider->setSliderPosition ( 0 );
+    if( !enable ) slider->setSliderPosition ( -1 );
     fasterButton->setEnabled( enable );
 
     /* Advanced Buttons too */

modules/gui/qt4/util/input_slider.cpp

@@ -56,7 +56,10 @@ InputSlider::InputSlider( Qt::Orientation q,QWidget *_parent ) :
 void InputSlider::setPosition( float pos, int a, int b )
 {
     if( pos == -1.0 )
+    {
         setEnabled( false );
+        b_sliding = false;
+    }
     else
         setEnabled( true );