C#

private void onMouseMove(object sender, MouseEventArgs e)
{
    if (e.Button == MouseButtons.Right)
    {
        prevMousePos = currMousePos;
        currMousePos = e.Location;

        Point delta = currMousePos - prevMousePos;

        //Do stuff with delta...

        Cursor.Position = prevMousePos;    //Problem!
    }
}

this.panel_RenderWindow.MouseMove -= this.onMouseMove;
Cursor.Position = prevMousePos;
this.panel_RenderWindow.MouseMove += new System.Windows.Forms.MouseEventHandler(this.onMouseMove);

private static bool IsEmailAllowed(string text)
        {
            bool blnValidEmail = false;
            Regex regEMail = new Regex(@"^[a-zA-Z][\w\.-]{2,28}[a-zA-Z0-9]@[a-zA-Z0-9][\w\.-]*[a-zA-Z0-9]\.[a-zA-Z][a-zA-Z\.]*[a-zA-Z]$");
            if (text.Length > 0)
            {
                blnValidEmail = regEMail.IsMatch(text);
            }

            return blnValidEmail;
        }
        
        private void txtEmail_LostFocus(object sender, RoutedEventArgs e)
        {
            if (IsEmailAllowed(txtEmail.Text.Trim()) == false)
            {
                MessageBox.Show("E-Mail expected", "Error", MessageBoxButton.OK, MessageBoxImage.Error);                    
                txtEmail.Focus();
            }
        }