R – In Silverlight why are some properties prefixed with x e.g x:name and some are not

Not sure how Linq to Xml is overkill. It is actually much easier to do Xml parsing with Linq2xml once you get the hang of it. I would say that regex or writing your own XmlNode would be overkill.

If you post some of the XmlNode work that you're doing I'm sure you would get some good translations. In the meantime, here is a good introduction to how easy it is to parse documents with Linq to Xml.

Update: In response to the issue being performance, all I could find was that linq to xml is faster than XmlDocument.

For item 1 and 2, the best way to get access to these input events is to create a custom TextBox deriving from the built in TextBox. Then you can override the OnKeyDown and OnMouseLeftButton down. From there you can either call the necessary code, or fire a new event. e.g.:

public class MyTextBox : TextBox
{
    public event MouseButtonEventHandler MySpecialMouseLeftButtonDown;

    protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e)
    {
        if (MySpecialMouseLeftButtonDown != null)
        {
            MySpecialMouseLeftButtonDown(this, e);
        }
        base.OnMouseLeftButtonDown(e);
    }
}

Similarly with OnKeyDown.