Qt: fix seekpoint bar when first chapter does not start at 0

Close #12416

modules/gui/qt4/util/input_slider.cpp

@@ -350,18 +350,17 @@ void SeekSlider::mouseMoveEvent( QMouseEvent *event )
         {
             QList<SeekPoint> points = chapters->getPoints();
             int i_selected = -1;
-                bool b_startsnonzero = false;
-                if ( points.count() > 0 )
-                    b_startsnonzero = ( points.at(0).time > 0 );
             for( int i = 0 ; i < points.count() ; i++ )
             {
                 int x = points.at(i).time / 1000000.0 / inputLength * size().width();
                 if ( event->x() >= x )
-                        i_selected = i + ( ( b_startsnonzero )? 1 : 0 );
+                    i_selected = i;
             }
             if ( i_selected >= 0 && i_selected < points.size() )
+            {
                 chapterLabel = points.at( i_selected ).name;
             }
+        }
 
         QPoint target( event->globalX() - ( event->x() - posX ),
                 QWidget::mapToGlobal( QPoint( 0, 0 ) ).y() );