C#

[StructLayout(LayoutKind.Sequential)]
public struct BrowseInfo
{
       public IntPtr hwndOwner;
       public IntPtr pidlRoot;
       [Out] public StringBuilder displayname;
       public string title;
       public int flags;
       public BrowseCallBackProc callback;
       public IntPtr lparam;
       public int iImage;
}

[DllImport("shell32.dll", CharSet=CharSet.Auto)]
static extern IntPtr SHBrowseForFolder(ref BROWSEINFO lpbi);

[StructLayout(LayoutKind.Explicit)]
public struct INPUT
{
  [FieldOffset(0), MarshalAs(UnmanagedType.U4)] public int type;
  [FieldOffset(4)] public MOUSEINPUT mi;
  [FieldOffset(4)] public KEYBOARDINPUT ki;
  // No need to declare HARDWAREINPUT since this is a union.
  // You would for proper bit alignment if it wasn't a union;
  // otherwise, you're shorting the execution stack.
}
 
[StructLayout(LayoutKind.Sequential)]
public struct MOUSEINPUT
{
  public int dx; // Unmanaged longs are managed ints (both 32 bits)
  public int dy;
  [MarshalAs(UnmanagedType.U4)] public int mouseData;
  [MarshalAs(UnmanagedType.U4)] public int dwFlags;
  [MarshalAs(UnmanagedType.U4)] public int time;
  [MarshalAs(UnmanagedType.SysUInt)] public IntPtr dwExtraInfo;
}
 
[StructLayout(LayoutKind.Sequential)]
public struct KEYBOARDINPUT
{
  public short wVk; // Could cast managed Keys enumeration to (short)
  public short wScan;
  [MarshalAs(UnmanagedType.U4)] public int dwFlags;
  [MarshalAs(UnmanagedType.U4)] public int time;
  [MarshalAs(UnmanagedType.SysUInt)] public IntPtr dwExtraInfo;
}