The StreamReader locks a text file whilst it is reading it.
Can I force the StreamReader to work in a \"read-only\" or \"non locking\" mode?
My workaround would
You can pass a FileStream to the StreamReader, and create the FileStream with the proper FileShare value. For instance:
using (var file = new FileStream (openFileDialog1.FileName, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
using (var reader = new StreamReader (file, Encoding.Unicode)) {
}