Hello, we have a big problem with Drag and Drop, Drag an Drop only works with WIndows Explorer after Upgrade. The old function with “FileDiscriptorW” is no longer working.
As our customers need this feature more than any other function in emclient we need a solution. We provide our customers em-client as a good working mail tool in order to work with our CRM/ERP and this was a crucial function that works with older versions without a problem.
So with what application drag and drop does not work exactly? What was the previous version when it worked?
Old Version was 8.2 .1721.0. Now we upgraded to 10.3.2619 (1e54f4a). Problem is that the FileDescriptorW seems not to hold the data now. HTML Data works with dragdrop, but filedrop, filedescriptor etc. seems not to be working.
Tested on Win Server 2016, 2019, Windows 10 + 11. I tried also different net framework versions. Please help us to make FileDescriptorW work as before.
Because we updated all customers to new version with a new license, we need to fix the issue or have to downgrade… 
The application is a self developed ERP-System which is based on .NET 4.8 Framework. If you want i can send you the C# Code of the FileDescriptorW Handler that has worked before.
Ok, so send the c# code. What exactly are you dragging? Emails, attachments? FileDecriptorW should still be there. We test the drag and drop feature regularly and it works with other applications.
private void Button1_DragDrop(object sender, DragEventArgs e)
{
MyDataObject obj = new MyDataObject(e.Data);
string[] fileNames = { };
//ThunderBird Does a FileDrop
if (obj.GetDataPresent(DataFormats.FileDrop, true))
{
string[] tempFileNames = (string[])obj.GetData(DataFormats.FileDrop);
List<string> tempFileNameList = new List<string>();
foreach (string f in tempFileNames)
{
tempFileNameList.Add(System.IO.Path.GetFileName(f));
}
fileNames = tempFileNameList.ToArray();
}
else if (fileNames.Length == 0)
{
//EM Client uses "FileGroupDescriptorW"
fileNames = (string[])obj.GetData("FileGroupDescriptorW");
}
else if (fileNames.Length == 0)
{
//Outlook Uses "FileGroupDescriptor"
fileNames = (string[])obj.GetData("FileGroupDescriptor");
}
int index = 0;
foreach (string file in fileNames)
{
InsertFile(file, obj.GetData("FileContents", index).ToArray());
index++;
}
ReadDocCount();
}
public class MyDataObject : System.Windows.Forms.IDataObject
{
#region NativeMethods
private class NativeMethods
{
[DllImport("kernel32.dll")]
public static extern IntPtr GlobalLock(IntPtr hMem);
[DllImport("kernel32.dll")]
public static extern IntPtr GlobalSize(IntPtr handle);
[DllImport("kernel32.dll")]
public static extern IntPtr GlobalUnlock(IntPtr hMem);
[DllImport("ole32.dll", PreserveSig = false)]
public static extern ILockBytes CreateILockBytesOnHGlobal(IntPtr hGlobal, bool fDeleteOnRelease);
[DllImport("OLE32.DLL", CharSet = CharSet.Auto, PreserveSig = false)]
public static extern IntPtr GetHGlobalFromILockBytes(ILockBytes pLockBytes);
[DllImport("OLE32.DLL", CharSet = CharSet.Unicode, PreserveSig = false)]
public static extern IStorage StgCreateDocfileOnILockBytes(ILockBytes plkbyt, uint grfMode, uint reserved);
[ComImport, InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("0000000B-0000-0000-C000-000000000046")]
public interface IStorage
{
[return: MarshalAs(UnmanagedType.Interface)]
IStream CreateStream([In, MarshalAs(UnmanagedType.BStr)] string pwcsName, [In, MarshalAs(UnmanagedType.U4)] int grfMode, [In, MarshalAs(UnmanagedType.U4)] int reserved1, [In, MarshalAs(UnmanagedType.U4)] int reserved2);
[return: MarshalAs(UnmanagedType.Interface)]
IStream OpenStream([In, MarshalAs(UnmanagedType.BStr)] string pwcsName, IntPtr reserved1, [In, MarshalAs(UnmanagedType.U4)] int grfMode, [In, MarshalAs(UnmanagedType.U4)] int reserved2);
[return: MarshalAs(UnmanagedType.Interface)]
IStorage CreateStorage([In, MarshalAs(UnmanagedType.BStr)] string pwcsName, [In, MarshalAs(UnmanagedType.U4)] int grfMode, [In, MarshalAs(UnmanagedType.U4)] int reserved1, [In, MarshalAs(UnmanagedType.U4)] int reserved2);
[return: MarshalAs(UnmanagedType.Interface)]
IStorage OpenStorage([In, MarshalAs(UnmanagedType.BStr)] string pwcsName, IntPtr pstgPriority, [In, MarshalAs(UnmanagedType.U4)] int grfMode, IntPtr snbExclude, [In, MarshalAs(UnmanagedType.U4)] int reserved);
void CopyTo(int ciidExclude, [In, MarshalAs(UnmanagedType.LPArray)] Guid[] pIIDExclude, IntPtr snbExclude, [In, MarshalAs(UnmanagedType.Interface)] IStorage stgDest);
void MoveElementTo([In, MarshalAs(UnmanagedType.BStr)] string pwcsName, [In, MarshalAs(UnmanagedType.Interface)] IStorage stgDest, [In, MarshalAs(UnmanagedType.BStr)] string pwcsNewName, [In, MarshalAs(UnmanagedType.U4)] int grfFlags);
void Commit(int grfCommitFlags);
void Revert();
void EnumElements([In, MarshalAs(UnmanagedType.U4)] int reserved1, IntPtr reserved2, [In, MarshalAs(UnmanagedType.U4)] int reserved3, [MarshalAs(UnmanagedType.Interface)] out object ppVal);
void DestroyElement([In, MarshalAs(UnmanagedType.BStr)] string pwcsName);
void RenameElement([In, MarshalAs(UnmanagedType.BStr)] string pwcsOldName, [In, MarshalAs(UnmanagedType.BStr)] string pwcsNewName);
void SetElementTimes([In, MarshalAs(UnmanagedType.BStr)] string pwcsName, [In] System.Runtime.InteropServices.ComTypes.FILETIME pctime, [In] System.Runtime.InteropServices.ComTypes.FILETIME patime, [In] System.Runtime.InteropServices.ComTypes.FILETIME pmtime);
void SetClass([In] ref Guid clsid);
void SetStateBits(int grfStateBits, int grfMask);
void Stat([Out] out System.Runtime.InteropServices.ComTypes.STATSTG pStatStg, int grfStatFlag);
}
[ComImport, Guid("0000000A-0000-0000-C000-000000000046"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
public interface ILockBytes
{
void ReadAt([In, MarshalAs(UnmanagedType.U8)] long ulOffset, [Out, MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 1)] byte[] pv, [In, MarshalAs(UnmanagedType.U4)] int cb, [Out, MarshalAs(UnmanagedType.LPArray)] int[] pcbRead);
void WriteAt([In, MarshalAs(UnmanagedType.U8)] long ulOffset, IntPtr pv, [In, MarshalAs(UnmanagedType.U4)] int cb, [Out, MarshalAs(UnmanagedType.LPArray)] int[] pcbWritten);
void Flush();
void SetSize([In, MarshalAs(UnmanagedType.U8)] long cb);
void LockRegion([In, MarshalAs(UnmanagedType.U8)] long libOffset, [In, MarshalAs(UnmanagedType.U8)] long cb, [In, MarshalAs(UnmanagedType.U4)] int dwLockType);
void UnlockRegion([In, MarshalAs(UnmanagedType.U8)] long libOffset, [In, MarshalAs(UnmanagedType.U8)] long cb, [In, MarshalAs(UnmanagedType.U4)] int dwLockType);
void Stat([Out] out System.Runtime.InteropServices.ComTypes.STATSTG pstatstg, [In, MarshalAs(UnmanagedType.U4)] int grfStatFlag);
}
[StructLayout(LayoutKind.Sequential)]
public sealed class POINTL
{
public int x;
public int y;
}
[StructLayout(LayoutKind.Sequential)]
public sealed class SIZEL
{
public int cx;
public int cy;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public sealed class FILEGROUPDESCRIPTORA
{
public uint cItems;
public FILEDESCRIPTORA[] fgd;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public sealed class FILEDESCRIPTORA
{
public uint dwFlags;
public Guid clsid;
public SIZEL sizel;
public POINTL pointl;
public uint dwFileAttributes;
public System.Runtime.InteropServices.ComTypes.FILETIME ftCreationTime;
public System.Runtime.InteropServices.ComTypes.FILETIME ftLastAccessTime;
public System.Runtime.InteropServices.ComTypes.FILETIME ftLastWriteTime;
public uint nFileSizeHigh;
public uint nFileSizeLow;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
public string cFileName;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public sealed class FILEGROUPDESCRIPTORW
{
public uint cItems;
public FILEDESCRIPTORW[] fgd;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public sealed class FILEDESCRIPTORW
{
public uint dwFlags;
public Guid clsid;
public SIZEL sizel;
public POINTL pointl;
public uint dwFileAttributes;
public System.Runtime.InteropServices.ComTypes.FILETIME ftCreationTime;
public System.Runtime.InteropServices.ComTypes.FILETIME ftLastAccessTime;
public System.Runtime.InteropServices.ComTypes.FILETIME ftLastWriteTime;
public uint nFileSizeHigh;
public uint nFileSizeLow;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
public string cFileName;
}
}
#endregion
#region Property(s)
/// <summary>
/// Holds the <see cref="System.Windows.Forms.IDataObject"/> that this class is wrapping
/// </summary>
private System.Windows.Forms.IDataObject underlyingDataObject;
private readonly System.Runtime.InteropServices.ComTypes.IDataObject comUnderlyingDataObject;
public System.Windows.Forms.IDataObject UnderlyingDataObject { get => underlyingDataObject; set => underlyingDataObject = value; }
#endregion
#region Constructor(s)
public MyDataObject(System.Windows.Forms.IDataObject underlyingDataObject)
{
this.underlyingDataObject = underlyingDataObject;
this.comUnderlyingDataObject = (System.Runtime.InteropServices.ComTypes.IDataObject)this.underlyingDataObject;
//FieldInfo innerDataField = this.underlyingDataObject.GetType().GetField("innerData", BindingFlags.NonPublic | BindingFlags.Instance);
//this.oleUnderlyingDataObject = (System.Windows.Forms.IDataObject)innerDataField.GetValue(this.underlyingDataObject);
//this.getDataFromHGLOBLALMethod = this.underlyingDataObject.GetType().GetMethod("GetDataFromHGLOBLAL", BindingFlags.NonPublic | BindingFlags.Instance);
}
#endregion
#region IDataObject Members
public object GetData(Type format)
{
return this.GetData(format.FullName);
}
public object GetData(string format)
{
return this.GetData(format, true);
}
public object GetData(string format, bool autoConvert)
{
switch (format)
{
case "FileGroupDescriptor":
IntPtr fileGroupDescriptorAPointer = IntPtr.Zero;
try
{
//use the underlying IDataObject to get the FileGroupDescriptor as a MemoryStream
MemoryStream fileGroupDescriptorStream = (MemoryStream)this.underlyingDataObject.GetData("FileGroupDescriptor", autoConvert);
byte[] fileGroupDescriptorBytes = new byte[fileGroupDescriptorStream.Length];
fileGroupDescriptorStream.Read(fileGroupDescriptorBytes, 0, fileGroupDescriptorBytes.Length);
fileGroupDescriptorStream.Close();
//copy the file group descriptor into unmanaged memory
fileGroupDescriptorAPointer = Marshal.AllocHGlobal(fileGroupDescriptorBytes.Length);
Marshal.Copy(fileGroupDescriptorBytes, 0, fileGroupDescriptorAPointer, fileGroupDescriptorBytes.Length);
//marshal the unmanaged memory to to FILEGROUPDESCRIPTORA struct
object fileGroupDescriptorObject = Marshal.PtrToStructure(fileGroupDescriptorAPointer, typeof(NativeMethods.FILEGROUPDESCRIPTORA));
NativeMethods.FILEGROUPDESCRIPTORA fileGroupDescriptor = (NativeMethods.FILEGROUPDESCRIPTORA)fileGroupDescriptorObject;
//create a new array to store file names in of the number of items in the file group descriptor
string[] fileNames = new string[fileGroupDescriptor.cItems];
//get the pointer to the first file descriptor
IntPtr fileDescriptorPointer = (IntPtr)((int)fileGroupDescriptorAPointer + Marshal.SizeOf(fileGroupDescriptor.cItems));
//loop for the number of files acording to the file group descriptor
for (int fileDescriptorIndex = 0; fileDescriptorIndex < fileGroupDescriptor.cItems; fileDescriptorIndex++)
{
//marshal the pointer top the file descriptor as a FILEDESCRIPTORA struct and get the file name
NativeMethods.FILEDESCRIPTORA fileDescriptor = (NativeMethods.FILEDESCRIPTORA)Marshal.PtrToStructure(fileDescriptorPointer, typeof(NativeMethods.FILEDESCRIPTORA));
fileNames[fileDescriptorIndex] = fileDescriptor.cFileName;
//move the file descriptor pointer to the next file descriptor
fileDescriptorPointer = (IntPtr)((int)fileDescriptorPointer + Marshal.SizeOf(fileDescriptor));
}
//return the array of filenames
return fileNames;
}
finally
{
//free unmanaged memory pointer
Marshal.FreeHGlobal(fileGroupDescriptorAPointer);
}
case "FileGroupDescriptorW":
//override the default handling of FileGroupDescriptorW which returns a
//MemoryStream and instead return a string array of file names
IntPtr fileGroupDescriptorWPointer = IntPtr.Zero;
try
{
//use the underlying IDataObject to get the FileGroupDescriptorW as a MemoryStream
MemoryStream fileGroupDescriptorStream = (MemoryStream)GetData("FileGroupDescriptorW", -1);
byte[] fileGroupDescriptorBytes = new byte[fileGroupDescriptorStream.Length];
fileGroupDescriptorStream.Read(fileGroupDescriptorBytes, 0, fileGroupDescriptorBytes.Length);
fileGroupDescriptorStream.Close();
//copy the file group descriptor into unmanaged memory
fileGroupDescriptorWPointer = Marshal.AllocHGlobal(fileGroupDescriptorBytes.Length);
Marshal.Copy(fileGroupDescriptorBytes, 0, fileGroupDescriptorWPointer, fileGroupDescriptorBytes.Length);
//marshal the unmanaged memory to to FILEGROUPDESCRIPTORW struct
object fileGroupDescriptorObject = Marshal.PtrToStructure(fileGroupDescriptorWPointer, typeof(NativeMethods.FILEGROUPDESCRIPTORW));
NativeMethods.FILEGROUPDESCRIPTORW fileGroupDescriptor = (NativeMethods.FILEGROUPDESCRIPTORW)fileGroupDescriptorObject;
//create a new array to store file names in of the number of items in the file group descriptor
string[] fileNames = new string[fileGroupDescriptor.cItems];
//get the pointer to the first file descriptor
//get the pointer to the first file descriptor
IntPtr fileDescriptorPointer = (IntPtr)((int)fileGroupDescriptorWPointer + Marshal.SizeOf(fileGroupDescriptor.cItems));
//loop for the number of files acording to the file group descriptor
for (int fileDescriptorIndex = 0; fileDescriptorIndex < fileGroupDescriptor.cItems; fileDescriptorIndex++)
{
//marshal the pointer top the file descriptor as a FILEDESCRIPTORW struct and get the file name
NativeMethods.FILEDESCRIPTORW fileDescriptor = (NativeMethods.FILEDESCRIPTORW)Marshal.PtrToStructure(fileDescriptorPointer, typeof(NativeMethods.FILEDESCRIPTORW));
fileNames[fileDescriptorIndex] = fileDescriptor.cFileName;
//move the file descriptor pointer to the next file descriptor
fileDescriptorPointer = (IntPtr)((int)fileDescriptorPointer + Marshal.SizeOf(fileDescriptor));
}
//return the array of filenames
return fileNames;
}
finally
{
//free unmanaged memory pointer
Marshal.FreeHGlobal(fileGroupDescriptorWPointer);
}
case "FileContents":
//override the default handling of FileContents which returns the
//contents of the first file as a memory stream and instead return
//a array of MemoryStreams containing the data to each file dropped
//get the array of filenames which lets us know how many file contents exist
string[] fileContentNames = (string[])this.GetData("FileGroupDescriptor");
//create a MemoryStream array to store the file contents
MemoryStream[] fileContents = new MemoryStream[fileContentNames.Length];
//loop for the number of files acording to the file names
for (int fileIndex = 0; fileIndex < fileContentNames.Length; fileIndex++)
{
//get the data at the file index and store in array
fileContents[fileIndex] = this.GetData(format, fileIndex);
}
//return array of MemoryStreams containing file contents
return fileContents;
}
//use underlying IDataObject to handle getting of data
return this.underlyingDataObject.GetData(format, autoConvert);
}
/// <summary>
/// Retrieves the data associated with the specified data format at the specified index.
/// </summary>
/// <param name="format">The format of the data to retrieve. See <see cref="T:System.Windows.Forms.DataFormats"></see> for predefined formats.</param>
/// <param name="index">The index of the data to retrieve.</param>
/// <returns>
/// A <see cref="MemoryStream"/> containing the raw data for the specified data format at the specified index.
/// </returns>
public MemoryStream GetData(string format, int index)
{
//create a FORMATETC struct to request the data with
FORMATETC formatetc = new FORMATETC();
formatetc.cfFormat = (short)DataFormats.GetFormat(format).Id;
formatetc.dwAspect = DVASPECT.DVASPECT_CONTENT;
formatetc.lindex = index;
formatetc.ptd = new IntPtr(0);
formatetc.tymed = TYMED.TYMED_ISTREAM | TYMED.TYMED_ISTORAGE | TYMED.TYMED_HGLOBAL;
//create STGMEDIUM to output request results into
STGMEDIUM medium = new STGMEDIUM();
//using the Com IDataObject interface get the data using the defined FORMATETC
this.comUnderlyingDataObject.GetData(ref formatetc, out medium);
//retrieve the data depending on the returned store type
switch (medium.tymed)
{
case TYMED.TYMED_ISTORAGE:
//to handle a IStorage it needs to be written into a second unmanaged
//memory mapped storage and then the data can be read from memory into
//a managed byte and returned as a MemoryStream
NativeMethods.IStorage iStorage = null;
NativeMethods.IStorage iStorage2 = null;
NativeMethods.ILockBytes iLockBytes = null;
System.Runtime.InteropServices.ComTypes.STATSTG iLockBytesStat;
try
{
//marshal the returned pointer to a IStorage object
iStorage = (NativeMethods.IStorage)Marshal.GetObjectForIUnknown(medium.unionmember);
Marshal.Release(medium.unionmember);
//create a ILockBytes (unmanaged byte array) and then create a IStorage using the byte array as a backing store
iLockBytes = NativeMethods.CreateILockBytesOnHGlobal(IntPtr.Zero, true);
iStorage2 = NativeMethods.StgCreateDocfileOnILockBytes(iLockBytes, 0x00001012, 0);
//copy the returned IStorage into the new IStorage
iStorage.CopyTo(0, null, IntPtr.Zero, iStorage2);
iLockBytes.Flush();
iStorage2.Commit(0);
//get the STATSTG of the ILockBytes to determine how many bytes were written to it
iLockBytesStat = new System.Runtime.InteropServices.ComTypes.STATSTG();
iLockBytes.Stat(out iLockBytesStat, 1);
int iLockBytesSize = (int)iLockBytesStat.cbSize;
//read the data from the ILockBytes (unmanaged byte array) into a managed byte array
byte[] iLockBytesContent = new byte[iLockBytesSize];
iLockBytes.ReadAt(0, iLockBytesContent, iLockBytesContent.Length, null);
//wrapped the managed byte array into a memory stream and return it
return new MemoryStream(iLockBytesContent);
}
finally
{
//release all unmanaged objects
Marshal.ReleaseComObject(iStorage2);
Marshal.ReleaseComObject(iLockBytes);
Marshal.ReleaseComObject(iStorage);
}
case TYMED.TYMED_ISTREAM:
//to handle a IStream it needs to be read into a managed byte and
//returned as a MemoryStream
IStream iStream = null;
System.Runtime.InteropServices.ComTypes.STATSTG iStreamStat;
try
{
//marshal the returned pointer to a IStream object
iStream = (IStream)Marshal.GetObjectForIUnknown(medium.unionmember);
Marshal.Release(medium.unionmember);
//get the STATSTG of the IStream to determine how many bytes are in it
iStreamStat = new System.Runtime.InteropServices.ComTypes.STATSTG();
iStream.Stat(out iStreamStat, 0);
int iStreamSize = (int)iStreamStat.cbSize;
//read the data from the IStream into a managed byte array
byte[] iStreamContent = new byte[iStreamSize];
iStream.Read(iStreamContent, iStreamContent.Length, IntPtr.Zero);
//wrapped the managed byte array into a memory stream and return it
return new MemoryStream(iStreamContent);
}
finally
{
//release all unmanaged objects
Marshal.ReleaseComObject(iStream);
}
case TYMED.TYMED_HGLOBAL:
IntPtr intPtr = NativeMethods.GlobalLock((IntPtr)medium.unionmember);
int size = (int)NativeMethods.GlobalSize(intPtr).ToInt32();
byte[] data = new byte[size];
Marshal.Copy(intPtr, data, 0, size);
NativeMethods.GlobalUnlock(intPtr);
return new MemoryStream(data);
//to handle a HGlobal the exisitng "GetDataFromHGLOBLAL" method is invoked via
//reflection
// return (MemoryStream)this.getDataFromHGLOBLALMethod.Invoke(this.oleUnderlyingDataObject, new object[] { DataFormats.GetFormat((short)formatetc.cfFormat).Name, medium.unionmember });
}
return null;
}
/// <summary>
/// Determines whether data stored in this instance is associated with, or can be converted to, the specified format.
/// </summary>
/// <param name="format">A <see cref="T:System.Type"></see> representing the format for which to check. See <see cref="T:System.Windows.Forms.DataFormats"></see> for predefined formats.</param>
/// <returns>
/// true if data stored in this instance is associated with, or can be converted to, the specified format; otherwise, false.
/// </returns>
public bool GetDataPresent(Type format)
{
return this.underlyingDataObject.GetDataPresent(format);
}
/// <summary>
/// Determines whether data stored in this instance is associated with, or can be converted to, the specified format.
/// </summary>
/// <param name="format">The format for which to check. See <see cref="T:System.Windows.Forms.DataFormats"></see> for predefined formats.</param>
/// <returns>
/// true if data stored in this instance is associated with, or can be converted to, the specified format; otherwise false.
/// </returns>
public bool GetDataPresent(string format)
{
return this.underlyingDataObject.GetDataPresent(format);
}
/// <summary>
/// Determines whether data stored in this instance is associated with the specified format, using a Boolean value to determine whether to convert the data to the format.
/// </summary>
/// <param name="format">The format for which to check. See <see cref="T:System.Windows.Forms.DataFormats"></see> for predefined formats.</param>
/// <param name="autoConvert">true to determine whether data stored in this instance can be converted to the specified format; false to check whether the data is in the specified format.</param>
/// <returns>
/// true if the data is in, or can be converted to, the specified format; otherwise, false.
/// </returns>
public bool GetDataPresent(string format, bool autoConvert)
{
return this.underlyingDataObject.GetDataPresent(format, autoConvert);
}
/// <summary>
/// Returns a list of all formats that data stored in this instance is associated with or can be converted to.
/// </summary>
/// <returns>
/// An array of the names that represents a list of all formats that are supported by the data stored in this object.
/// </returns>
public string[] GetFormats()
{
return this.underlyingDataObject.GetFormats();
}
public string[] GetFormats(bool autoConvert)
{
return this.underlyingDataObject.GetFormats(autoConvert);
}
/// <summary>
/// Stores the specified data in this instance, using the class of the data for the format.
/// </summary>
/// <param name="data">The data to store.</param>
public void SetData(object data)
{
this.underlyingDataObject.SetData(data);
}
/// <summary>
/// Stores the specified data and its associated class type in this instance.
/// </summary>
/// <param name="format">A <see cref="T:System.Type"></see> representing the format associated with the data. See <see cref="T:System.Windows.Forms.DataFormats"></see> for predefined formats.</param>
/// <param name="data">The data to store.</param>
public void SetData(Type format, object data)
{
this.underlyingDataObject.SetData(format, data);
}
/// <summary>
/// Stores the specified data and its associated format in this instance.
/// </summary>
/// <param name="format">The format associated with the data. See <see cref="T:System.Windows.Forms.DataFormats"></see> for predefined formats.</param>
/// <param name="data">The data to store.</param>
public void SetData(string format, object data)
{
this.underlyingDataObject.SetData(format, data);
}
/// <summary>
/// Stores the specified data and its associated format in this instance, using a Boolean value to specify whether the data can be converted to another format.
/// </summary>
/// <param name="format">The format associated with the data. See <see cref="T:System.Windows.Forms.DataFormats"></see> for predefined formats.</param>
/// <param name="autoConvert">true to allow the data to be converted to another format; otherwise, false.</param>
/// <param name="data">The data to store.</param>
public void SetData(string format, bool autoConvert, object data)
{
this.underlyingDataObject.SetData(format, autoConvert, data);
}
#endregion
}
This code has worked without any problems until the update 
We drop Emails, PDFs, XMLs and other Attachments. Customer is very disappointed because its working with all the tools except emclient. And i get questions why he paid for something “unusable”…
Does it work if you first drag the file from eM Client to the Windows desktop, and then drag it to your other application?
Yes, it is working from Outlook, Thunderbird, Windows Desktop and anything else we have testet…
The code has multiple flaws that prevent it from working. I couldn’t even get it to accept files dragged from Windows Explorer.
Firstly, both FILEGROUPDESCRIPTORA and FILEGROUPDESCRIPTORW declare a member name fgd with unspecified size. This member cannot be marshalled with Marshal.PtrToStructure and it will throw ExecutionEngineException on any modern .NET. The member is not used anyway, so you can comment it out.
Secondly, there’re multiple invalid casts on pointer like (IntPtr)((int)fileDescriptorPointer .... On 64-bit applications this will truncate the pointer value and try to access invalid memory. Remove the (int) cast to fix it.
With these bugs fixed I was able to drop files from both Windows Explorer and eM Client.
Thank you very much, this was great support… Thank you all
Everything is workiing again.
By the way, what is the product’s name?