Using C # and geckofx autoselect file to upload

internal class myFileDialog: nsIFilePicker, IDisposable
        {
            nsIFilePicker filePicker = null;

            public myFileDialog(): base()
            {
                filePicker = _filepicker;
            }

            short _mode = 0;
            public void Init(nsIDOMWindow parent, nsAStringBase title, short mode)
            {
                _mode = mode;
                //_mode = 0;
                filePicker.Init(parent, title, mode);
            }

            public void AppendFilters(int filterMask)
            {
            }

            public void AppendFilter(nsAStringBase title, nsAStringBase filter)
            {
            }

            public void GetDefaultStringAttribute(nsAStringBase aDefaultString)
            {
            }

            public void SetDefaultStringAttribute(nsAStringBase aDefaultString)
            {
            }

            public void GetDefaultExtensionAttribute(nsAStringBase aDefaultExtension)
            {
            }

            public void SetDefaultExtensionAttribute(nsAStringBase aDefaultExtension)
            {
            }

            public int GetFilterIndexAttribute()
            {
                return -1;
            }

            public void SetFilterIndexAttribute(int aFilterIndex)
            {
            }

            public nsIFile GetDisplayDirectoryAttribute()
            {
                throw new NotImplementedException();
            }

            public void SetDisplayDirectoryAttribute(nsIFile aDisplayDirectory)
            {
            }

            public nsIFile GetFileAttribute()
            {
                throw new NotImplementedException();
            }

            public nsIURI GetFileURLAttribute()
            {
                throw new NotImplementedException();
            }

            public nsISimpleEnumerator GetFilesAttribute()
            {
                //return this.filePicker.GetFilesAttribute();
                return new myFilesEnum(this.filePicker.GetFilesAttribute()); 
            }

            public nsISupports GetDomfileAttribute()
            {
                return this.filePicker.GetDomfileAttribute();
                throw new NotImplementedException();
            }

            public nsISimpleEnumerator GetDomfilesAttribute() //<----- here solution
            {
                //_filepicker = Xpcom.CreateInstance<nsIFilePicker>("@mozilla.org/filepicker;1");
                //nsISimpleEnumerator nsie = Xpcom.CreateInstance<nsISimpleEnumerator>("@mozilla.org/SimpleEnumerator;1");
                //nsISimpleEnumerator rst = this.filePicker.GetDomfilesAttribute();
                //nsISupports s = rst.GetNext();
                //nsILocalFile fl = Xpcom.QueryInterface<nsILocalFile>(s);
                //return rst;
                //nsISimpleEnumerator xb = new myFilesEnum();
                nsISimpleEnumerator r = this.filePicker.GetDomfilesAttribute();
                //nsISupports rs = r.GetNext();
                
                //return r;
                return new myFilesEnum(this.filePicker.GetDomfilesAttribute());                
            }

            public bool GetAddToRecentDocsAttribute()
            {
                throw new NotImplementedException();
            }

            public void SetAddToRecentDocsAttribute(bool aAddToRecentDocs)
            {
                throw new NotImplementedException();
            }

            public short Show()
            {
                return 0;
            }

            public void Open(nsIFilePickerShownCallback aFilePickerShownCallback)
            {
                this.filePicker.Open(aFilePickerShownCallback);
                //aFilePickerShownCallback.Done(0);
            }

            public short GetModeAttribute()
            {
                //return 0;
                return _mode;
            }
            
            public void Dispose()
            {
                
            }
        }