C#

FileStream fs = new FileStream("\\Server\Share\File.txt", FileMode.Open);

DataObject do = new DataObject(".NETControl", this);
this.DoDragDrop(do, DragDropEffects.Move);

protected override void OnDragOver(DragEventArgs e)
{
  // The following dictates that the object can be dropped if supported.
  if (e.Data.GetDataPresent(".NETControl") &&
      (e.AllowedEffect & DragDropEffects.Move) != 0)
    e.Effect = DragDropEffects.Move;
}
protected override void OnDragDrop(DragEventArgs e)
{
  if (e.Data.GetDataPresent(".NETControl") &&
      (e.AllowedEffect & DragDropEffects.Move) != 0)
  {
    Control c = (Control)e.Data.GetData(".NETControl");
    c.Location = new Point(e.X, e.Y);
  }
}

typedef struct FARSTRUCT tagSAFEARRAY {
   unsigned short cDims;       // Count of dimensions in this array.
   unsigned short fFeatures;   // Flags used by the SafeArray
                        // routines documented below.
#if defined(WIN32)
   unsigned long cbElements;   // Size of an element of the array.
                        // Does not include size of
                        // pointed-to data.
   unsigned long cLocks;      // Number of times the array has been 
                        // locked without corresponding unlock.
#else
   unsigned short cbElements;
   unsigned short cLocks;
   unsigned long handle;      // Used on Macintosh only.
#endif
   void HUGEP* pvData;             // Pointer to the data.
   SAFEARRAYBOUND rgsabound[1];      // One bound for each dimension.
} SAFEARRAY;

BOOL GetComputerName(/*[out]*/ LPTSTR lpBuffer, /*[in,out]*/ LPDWORD lpnSize);

[DllImport("user32.dll", CharSet=CharSet.Auto)]
private static extern bool GetComputerName(string buffer,
  [MarshalAs(UnmanagedType.U4)] ref int size);
//...
int size = 16;
string buffer = new string(size, '\0'); // Initialize to null chars.
GetComputerName(buffer, ref size);