title: How to apply SharpMap.VectorStyle theme on VectorLayer if DataSource is FeatureDataTable?
body: <p>I tried Vector Layer theme when I used ShapeFile as data source for vector layer. But when I am trying to achieve same thing with custom polygon data it is not working.</p>
  
  <p>Below is the code I used:</p>
  
  <pre class="lang-cs prettyprint-override"><code>Dictionary&lt;string, SharpMap.Styles.IStyle&gt; styles = new Dictionary&lt;string, SharpMap.Styles.IStyle&gt;();
                  styles.Clear();
                  styles.Add("NONE", m_noneStyleDefault);
                  foreach (ListViewItem tn in _arlv)
                  {
                      DataRow _row = (DataRow)tn.Tag;
                      r = labelData.NewRow();
                      var wkbreader = new NetTopologySuite.IO.WKTReader();
                      var geom = wkbreader.Read(_row["ogr_geometry"].ToString());
                      r["FID"] = (Int32)_row["ogr_fid"];
                      r["NAME"] = _row["sovereignt"].ToString();
                      r["SOV_A3"] = _row["sov_a3"].ToString().Trim().ToUpper();
                      r["TYPE"] = _row["mytype"].ToString();
                      r.Geometry = geom;
  
                      labelData.Rows.Add(r);
                      styles.Add(_row["sov_a3"].ToString().Trim().ToUpper(), m_selectStyleDefault);
                  }
  
                  m_vlCountries.DataSource = new SharpMap.Data.Providers.GeometryProvider(labelData);
                  //m_vlCountries.Style = m_selectStyleDefault;
  
                  m_vlCountries.Theme = new SharpMap.Rendering.Thematics.UniqueValuesTheme&lt;string&gt;("SOV_A3", styles, m_noneStyleDefault);
  </code></pre>