找到点下面的所有窗口

要做到这一点：

>在拖动的窗口中处理WM_NCHITTEST
>在拖动过程中返回HTTRANSPARENT.否则调用默认窗口proc.
> WindowFromPoint will ignore HTTRANSPARENT窗口,但只有那些属于调用线程的窗口.这应该不是一个问题,因为你应该从窗口所有者线程调用WindowFromPoint.
>确保传递给WindowFromPoint的点没有子窗口,或者也为这些子窗口处理WM_NCHITTEST.

故障排除(如果您仍然从WindowFromPoint获取窗口)

>测试GetCurrentThreadID()== GetWindowThreadProcessId(WindowFromPoint(),0)以确保从正确的线程调用
>在WM_NCHITTEST中,测试hwnd参数等于从WindowFromPoint()获得的值

示例(矩形内的区域从WindowFromPoint返回基础窗口)：

LRESULT CALLBACK WndProc(HWND hWnd,UINT message,WPARAM wParam,LPARAM lParam)
{
    static const RECT s_TransparentRect = {100,100,200,200};

    switch (message)
    {
    case WM_NCCREATE:
        SetTimer(hWnd,1,0);
        break;
    case WM_TIMER:
        {
            POINT cursorPos;
            GetCursorPos(&cursorPos);

            TCHAR buffer[256];
            _snwprintf_s(buffer,_countof(buffer),_TRUNCATE,_T("WindowFromPoint: %08Xn"),(int)WindowFromPoint(cursorPos));
            SetWindowText(hWnd,buffer);
        }
        break;
    case WM_PAINT:
        {
            PAINTSTRUCT ps;
            BeginPaint(hWnd,&ps);
            Rectangle(ps.hdc,s_TransparentRect.left,s_TransparentRect.top,s_TransparentRect.right,s_TransparentRect.bottom);
            EndPaint(hWnd,&ps);
        }
        break;
    case WM_NCHITTEST:
        {
            POINT cursorPos;
            GetCursorPos(&cursorPos);
            MapWindowPoints(HWND_DESKTOP,hWnd,&cursorPos,1);

            if (PtInRect(&s_TransparentRect,cursorPos))
                return HTTRANSPARENT;
        }
        break;
    }

    return DefWindowProc(hWnd,message,wParam,lParam);
}