窗口滚动条:窗口内置的滚动条绘制方法?

我绘的太难看啦，大家觉得应该怎么绘制呢？

响应了一堆消息 ，最后还是绘制不好，那位有这方面经验的给小弟指点指点,有例子更好，PS:不能通过新建窗口替换的方法

case WM_MOVE:
case WM_PAINT:
case WM_NCPAINT:
case WM_NCACTIVATE:
case WM_NOTIFY:

case WM_NCLBUTTONUP:case WM_NCLBUTTONDOWN:
case WM_NCRBUTTONDOWN: case WM_NCRBUTTONUP:
case WM_NCMBUTTONDOWN: case WM_NCMBUTTONUP:
case WM_NCLBUTTONDBLCLK:case WM_NCMOUSEMOVE:

延伸阅读