Create an interface with a url property like this :
public interface IUrlOwner
{
Uri Url
{
get;
set;
}
}
Then make your form implement this interface. So the form will know which url to open.
like this :
public partial class DrawingWindow : Form,IUrlOwner
Of course you have to implement the interface. so you need a concrete getter and setter.
Then you can cast the sender to the interface and get to the url in your event handler.
(sender as IUrlOwner)Url
My code is more like C# but I hope you know enough about VB.NET to understand what is going on here.