If using a single Smart UI operator across multiple screens (for setting up multiple screens see here), to remove the windows border insert the following line of code in the main subroutine of the default graphic form.
((Form)((UserControl)VIZNET.UI.Runtime.ObjectManager.GetInstance().VIZNETMain).Parent).FormBorderStyle = FormBorderStyle.None;
NOTE - this code snippet will only work if the default code language is C#.