Windows API相關，常用於P/Invoke

SystemParametersInfo

檢索或設置某個系統範圍參數的值。此功能還可以在設置參數時更新用戶配置文件。
SystemParametersInfoW function (winuser.h)

以編程方式更新桌面“拖動時顯示窗口內容”設置

public static class MsHelper
{
    [DllImport("user32.dll", SetLastError = true)]
    public static extern bool SystemParametersInfo(uint uiAction, uint uiParam, ref bool pvParam, SPIF fWinIni);

    //public const uint SPI_GETDRAGFULLWINDOWS = 0x0037;
    //public const uint SPI_SETDRAGFULLWINDOWS = 0x0038;
    public const uint SPI_GETDRAGFULLWINDOWS = 0x0026;
    public const uint SPI_SETDRAGFULLWINDOWS = 0x0025;

    public static bool GetDragFullWindows()
    {
        bool enabled = false;
        SystemParametersInfo(SPI_GETDRAGFULLWINDOWS, 0, ref enabled, 0);
        return enabled;
    }

    public static void ChangeDragFullWindows(bool enable)
    {
        SystemParametersInfo(SPI_SETDRAGFULLWINDOWS, enable ? 1u : 0, ref enable, SPIF.SPIF_SENDCHANGE);
    }
}
[Flags]
public enum SPIF
{
    SPIF_NONE = 0,
    SPIF_SENDCHANGE = 0x2,
    SPIF_UPDATEINIFILE = 0x1
}

參考：Update desktop "show window contents while dragging" setting programatically