- verticalScrollBar()->setRange(0,
- _viewport->get_total_height() + SignalMargin -
- areaSize.height());
+
+ const pair<int, int> extents = v_extents();
+ const int extra_scroll_height = (extents.second - extents.first) / 4;
+ verticalScrollBar()->setRange(extents.first - extra_scroll_height,
+ extents.first + extra_scroll_height);