Qt: fix a sticking slider issue.

Close #3105

modules/gui/qt4/util/input_slider.cpp

@@ -42,17 +42,22 @@ InputSlider::InputSlider( Qt::Orientation q, QWidget *_parent ) :
 {
     b_isSliding = false;
     lastSeeked  = 0;
+
     timer = new QTimer(this);
     timer->setSingleShot(true);
-    setMinimum( 0 );
-    setMouseTracking(true);
-    setMaximum( 1000 );
+
+    /* Properties */
+    setRange( 0, 1000 );
     setSingleStep( 2 );
     setPageStep( 10 );
+    setMouseTracking(true);
     setTracking( true );
+    setFocusPolicy( Qt::NoFocus );
+
+    /* Init to 0 */
     setPosition( -1.0, 0, 0 );
     secstotimestr( psz_length, 0 );
-    setFocusPolicy( Qt::NoFocus );
+
     CONNECT( this, valueChanged(int), this, userDrag( int ) );
     CONNECT( timer, timeout(), this, seekTick() );
 }
@@ -60,7 +65,10 @@ InputSlider::InputSlider( Qt::Orientation q, QWidget *_parent ) :
 void InputSlider::setPosition( float pos, int a, int b )
 {
     if( pos == -1.0 )
+    {
         setEnabled( false );
+        b_isSliding = false;
+    }
     else
         setEnabled( true );
 
@@ -78,7 +86,8 @@ void InputSlider::userDrag( int new_value )
 
 void InputSlider::seekTick()
 {
-    if( value() != lastSeeked ) {
+    if( value() != lastSeeked )
+    {
         lastSeeked = value();
         float f_pos = (float)(lastSeeked)/1000.0;
         emit sliderDragged( f_pos );