sometimes i need to open radwindow from server side, I use this code snippet from Telerik:

protected void Button1_Click(object sender, EventArgs e)
{
Telerik.WebControls.RadWindow newwindow = new Telerik.WebControls.RadWindow();
newwindow.ID = "RadWindow1";
newwindow.NavigateUrl = "http://www.google.com";
newwindow.VisibleOnPageLoad = true;
RadWindowManager1.Windows.Add(newwindow);
}

the intellisense in Visual Studio 2010 doesn't give me "width" or "height" when i try to see if it is allowed to specifiy size for radwindow. The answer is YES, forget about the intellisense, just type it in, there you are, worked!

newwindow.Width = Unit.Pixel(500);
newwindow.Height = Unit.Pixel(500);
newwindow.Behaviors = WindowBehaviors.Move | WindowBehaviors.Close;