title: How to add new items to combobox which is bound to Entities?
body: <p>Design class which is generated by C# :</p>
  
  <pre><code>    // 
      // usepurposeComboBox
      // 
      this.usepurposeComboBox.DataSource = this.usepurposeBindingSource;
      this.usepurposeComboBox.DisplayMember = "Name";
      this.usepurposeComboBox.FormattingEnabled = true;
      this.usepurposeComboBox.Location = new System.Drawing.Point(277, 53);
      this.usepurposeComboBox.Name = "usepurposeComboBox";
      this.usepurposeComboBox.Size = new System.Drawing.Size(218, 21);
      this.usepurposeComboBox.TabIndex = 4;
      this.usepurposeComboBox.ValueMember = "id";
      // 
      // usepurposeBindingSource
      // 
      this.usepurposeBindingSource.DataSource = typeof(mydatabaseEntities.usepurpose);
  </code></pre>
  
  <p>Then I bound the BindingSource (usepurposeBindingSource) to Entities :</p>
  
  <pre><code>usepurposeBindingSource.DataSource = mydatabaseEntities.usepurposes;
  </code></pre>
  
  <p>And I can not add a new row to usepurposeComboBox because it's been bound. Is there a workaround ?</p>