private void FormThumbnailView_FormClosed(object sender, FormClosedEventArgs e)
        {
            if (sender is Form form)
            {
                form.Dispose();
            }

            _formThumbnailView = null;
            GC.Collect();
        }
 private void openThumbnailsToolStripMenuItem1_Click(object sender, EventArgs e)
 {
     if (_formThumbnailView == null)
     {
         //_formThumbnailView = new FormThumbnailView(_formAddBookmark, _applicationSettingsService, _imageCacheService,);
         _formThumbnailView = _scope.Resolve <FormThumbnailView>();
         _formThumbnailView.Show();
         _formThumbnailView.FormClosed += FormThumbnailView_FormClosed;
     }
     else
     {
         _formThumbnailView.Focus();
     }
 }