Do not skip rows in when clicking the empty area of the scroll bar

The height of the header widget must be subtracted from the view's
height in Details View to determine the "pageStep" for the scroll bar.

BUG: 315619
FIXED-IN: 4.10.2
REVIEW: 109210

src/kitemviews/kitemlistcontainer.cpp

@@ -261,7 +261,9 @@ void KItemListContainer::updateScrollOffsetScrollBar()
         smoothScroller = m_verticalSmoothScroller;
         scrollOffsetScrollBar = verticalScrollBar();
         singleStep = view->itemSize().height();
-        pageStep = view->size().height();
+        // We cannot use view->size().height() because this height might
+        // include the header widget, which is not part of the scrolled area.
+        pageStep = view->verticalPageStep();
     } else {
         smoothScroller = m_horizontalSmoothScroller;
         scrollOffsetScrollBar = horizontalScrollBar();

src/kitemviews/kitemlistview.cpp

@@ -388,6 +388,15 @@ void KItemListView::setGeometry(const QRectF& rect)
     }
 }
 
+qreal KItemListView::verticalPageStep() const
+{
+    qreal headerHeight = 0;
+    if (m_headerWidget->isVisible()) {
+        headerHeight = m_headerWidget->size().height();
+    }
+    return size().height() - headerHeight;
+}
+
 int KItemListView::itemAt(const QPointF& pos) const
 {
     QHashIterator<int, KItemListWidget*> it(m_visibleItems);

src/kitemviews/kitemlistview.h

@@ -162,6 +162,12 @@ public:
     /** @reimp */
     virtual void setGeometry(const QRectF& rect);
 
+    /**
+     * @return The page step which should be used by the vertical scroll bar.
+     *         This is the height of the view except for the header widget.
+     */
+    qreal verticalPageStep() const;
+
     /**
      * @return Index of the item that is below the point \a pos.
      *         The position is relative to the upper right of