用这一句代码为什么不能使ShellListView向下滚动？

Question

窗体上放了个ShellListView控件，想用下面的语句让ShellListView向下滚动，但执行后没反应，是哪的问题？SendMessage(ShellListView1.Handle,WM_VSCROLL,10,10);

Answer 1

  SendMessage(ShellListView1.Handle,WM_VSCROLL,SB_LINEDOWN,0);

Answer 2

SendMessage(ShellListView1.Handle,WM_VSCROLL,SB_LINEDOWN,0); 下移
SendMessage(ShellListView1.Handle,WM_VSCROLL,SB_LINEUP,0);   上移
SendMessage(ShellListView1.Handle,WM_VSCROLL,SB_BOTTOM,0);   直接移到最下面 
SendMessage(ShellListView1.Handle,WM_VSCROLL,SB_TOP,0);      直接移到最上面 

Answer 3

Viewstyle属性设置为vsReport后
SendMessage(ShellListView1.Handle,WM_VSCROLL,SB_LINEDOWN,0);
一次向下移动一行