QAbstractSlider *vbar = verticalScrollBar();
Q_ASSERT(vbar);
if(vbar->maximum() - vbar->value() <= (offset + 5) * _currentScaleFactor ) { // 5px grace area
QAbstractSlider *vbar = verticalScrollBar();
Q_ASSERT(vbar);
if(vbar->maximum() - vbar->value() <= (offset + 5) * _currentScaleFactor ) { // 5px grace area