Code Snippet
Form1 f = null;
private void ThisDocument_Startup(object sender, System.EventArgs e)
{
this.Application.WindowSize += new Microsoft.Office.Interop.Word.ApplicationEvents4_WindowSizeEventHandler(Application_WindowSize);
f = new Form1();
f.Show();
f.Left = System.Convert.ToInt32(this.ActiveWindow.Left*1.33);
f.Top = System.Convert.ToInt32((this.ActiveWindow.Top + this.ActiveWindow.Height)*1.33-f.Height);
}
//Word and Winform have a different mesure of their location, so I multiply 1.33
void Application_WindowSize(Microsoft.Office.Interop.Word.Document Doc, Microsoft.Office.Interop.Word.Window Wn)
{
f.Left = System.Convert.ToInt32(this.ActiveWindow.Left * 1.33);
f.Top = System.Convert.ToInt32((this.ActiveWindow.Top + this.ActiveWindow.Height) * 1.33 - f.Height);
f.Activate();
}