Disabling MouseWheel behavior

kill_mousewheel.cs

// in form InitializeComponent(), or in the form's constructor
this.cboBox.MouseWheel += new System.Windows.Forms.MouseEventHandler(this.cboBox_MouseWheel);

// event implementation
private void cboBox_MouseWheel(object sender, System.Windows.Forms.MouseEventArgs e)
{
   HandledMouseEventArgs mouseWheelEvent = (HandledMouseEventArgs)e;
   mouseWheelEvent.Handled = true;
}