However, because the SetScrollInfo, SetScrollPos, SetScrollRange, GetScrollInfo, GetScrollPos, and GetScrollRange functions support 32-bit scroll bar position data, there is a way to circumvent the 16-bit barrier of the WM_HSCROLL and WM_VSCROLL messages. See GetScrollInfo for a description of the technique.
msdn说的似乎可以解决,但是我测试总是不成功,麻烦再看看。
http://msdn.microsoft.com/en-us/library/windows/desktop/bb787599(v=vs.85).aspx
Because the messages that indicate scroll bar position, WM_HSCROLL and WM_VSCROLL, are limited to 16 bits of position data, applications that rely solely on those messages for position data have a practical maximum value of 65,535 for the SetScrollRange function's nMaxPos parameter.
操作系统就是这么限制的。