M_START
case M_START:
? NodeGroup::M_ROLL : NodeGroup::M_START;
m_startButton->Message()->what = NodeGroup::M_START;
m = new BMessage(NodeGroup::M_START);
(M_WRITABLE(m) ? ((m)->m_data - M_START(m)) : 0)
#define M_TRAILINGROOM(m) ((M_START(m) + M_SIZE(m)) - ((m)->m_data + (m)->m_len))
KASSERT(m->m_data == M_START(m), (msg, __func__));
a = M_START(m);
#define M_DATABUF(m) M_START(m)