m_vScroll
AddChild(m_vScroll);
if (m_vScroll) {
m_vScroll->SetRange(0.0, 0.0);
m_vScroll->SetProportion(1.0);
m_vScroll->SetRange(m_dataRect.top, m_dataRect.bottom - height);
m_vScroll->SetProportion(height / m_dataRect.Height());
m_vScroll = new BScrollBar(
BScrollBar* m_vScroll;