You cannot control the behavior that occurs when a user presses ENTER when you add a ToolStripComboBox control to a Windows Application project that uses the .NET Framework 2.0 (905720)

WORKAROUND

• Add a KeyUp event handler to the ToolStripComboBox control. To do this, use code that resembles the following code example.

  private void toolStripComboBox1_KeyUp(object sender, KeyEventArgs e)
  {
  	if (e.KeyData == Keys.Enter)
  	{
  		MessageBox.Show("ENTER");
  	};
  } 

• Create a custom ToolStripComboBox control that encapsulates a custom ComboBox control. In this custom ComboBox control, override the IsInputKey method to capture the ENTER key. To do this, use code that resembles the following code example.

  protected override bool IsInputKey(System.Windows.Forms.Keys keyData)
  {
  	if(keyData == Keys.Enter){
  		return true;
  	}else{
  		return false;
  	}
  }