wpf dual monitor

public partial class app : system.windows.application
    {

        protected override void onstartup(startupeventargs e)
        {
            base.onstartup(e);           

            setupwindows();
        }
         
        private void setupwindows()
        {
            system.windows.forms.screen mainscreen = screen.allscreens[0]; ;
            winleft leftwin = new winleft()
            {
                windowstartuplocation = windowstartuplocation.manual,
                windowstate = system.windows.windowstate.normal,
                left = mainscreen.workingarea.left,
                top = mainscreen.workingarea.top,
                width = mainscreen.workingarea.width,
                height = mainscreen.workingarea.height
            };           

            system.windows.forms.screen secondaryscreen = screen.allscreens[1];
            winright rightwin = new winright()
            {
                windowstartuplocation = windowstartuplocation.manual,
                windowstate = system.windows.windowstate.normal,
                left = secondaryscreen.workingarea.left,
                top = secondaryscreen.workingarea.top,
                width = secondaryscreen.workingarea.width,
                height = secondaryscreen.workingarea.height
            };

           
            leftwin.show();
            leftwin.windowstate = windowstate.maximized;
            rightwin.show();
            rightwin.windowstate = windowstate.maximized;
            rightwin.owner = leftwin;
        }
    }