The true way of selecting multiple files in Explorer is the next
Unmanaged code looks like this (compiled from China code posts with fixing its bugs)
static class NativeMethods
{
[DllImport("shell32.dll", ExactSpelling = true)]
public static extern int SHOpenFolderAndSelectItems(
IntPtr pidlFolder,
uint cidl,
[In, MarshalAs(UnmanagedType.LPArray)] IntPtr[] apidl,
uint dwFlags);
[DllImport("shell32.dll", CharSet = CharSet.Auto)]
public static extern IntPtr ILCreateFromPath([MarshalAs(UnmanagedType.LPTStr)] string pszPath);
[ComImport]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
[Guid("000214F9-0000-0000-C000-000000000046")]
public interface IShellLinkW
{
[PreserveSig]
int GetPath(StringBuilder pszFile, int cch, [In, Out] ref WIN32_FIND_DATAW pfd, uint fFlags);
[PreserveSig]
int GetIDList([Out] out IntPtr ppidl);
[PreserveSig]
int SetIDList([In] ref IntPtr pidl);
[PreserveSig]
int GetDescription(StringBuilder pszName, int cch);
[PreserveSig]
int SetDescription([MarshalAs(UnmanagedType.LPWStr)] string pszName);
[PreserveSig]
int GetWorkingDirectory(StringBuilder pszDir, int cch);
[PreserveSig]
int SetWorkingDirectory([MarshalAs(UnmanagedType.LPWStr)] string pszDir);
[PreserveSig]
int GetArguments(StringBuilder pszArgs, int cch);
[PreserveSig]
int SetArguments([MarshalAs(UnmanagedType.LPWStr)] string pszArgs);
[PreserveSig]
int GetHotkey([Out] out ushort pwHotkey);
[PreserveSig]
int SetHotkey(ushort wHotkey);
[PreserveSig]
int GetShowCmd([Out] out int piShowCmd);
[PreserveSig]
int SetShowCmd(int iShowCmd);
[PreserveSig]
int GetIconLocation(StringBuilder pszIconPath, int cch, [Out] out int piIcon);
[PreserveSig]
int SetIconLocation([MarshalAs(UnmanagedType.LPWStr)] string pszIconPath, int iIcon);
[PreserveSig]
int SetRelativePath([MarshalAs(UnmanagedType.LPWStr)] string pszPathRel, uint dwReserved);
[PreserveSig]
int Resolve(IntPtr hwnd, uint fFlags);
[PreserveSig]
int SetPath([MarshalAs(UnmanagedType.LPWStr)] string pszFile);
}
[Serializable, StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode), BestFitMapping(false)]
public struct WIN32_FIND_DATAW
{
public uint dwFileAttributes;
public FILETIME ftCreationTime;
public FILETIME ftLastAccessTime;
public FILETIME ftLastWriteTime;
public uint nFileSizeHigh;
public uint nFileSizeLow;
public uint dwReserved0;
public uint dwReserved1;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
public string cFileName;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 14)]
public string cAlternateFileName;
}
public static void OpenFolderAndSelectFiles(string folder, params string[] filesToSelect)
{
IntPtr dir = ILCreateFromPath(folder);
var filesToSelectIntPtrs = new IntPtr[filesToSelect.Length];
for (int i = 0; i < filesToSelect.Length; i++)
{
filesToSelectIntPtrs[i] = ILCreateFromPath(filesToSelect[i]);
}
SHOpenFolderAndSelectItems(dir, (uint) filesToSelect.Length, filesToSelectIntPtrs, 0);
ReleaseComObject(dir);
ReleaseComObject(filesToSelectIntPtrs);
}
private static void ReleaseComObject(params object[] comObjs)
{
foreach (object obj in comObjs)
{
if (obj != null && Marshal.IsComObject(obj))
Marshal.ReleaseComObject(obj);
}
}
}