How to set foreground window over XBMC fullscreen mode

Question

I write simple XBMC script to launch my application (C#) ,My C# app will hidden XBMC by call ShowWindow (w32 api).

Between XBMC was hidden it also gain focus, when press any key all action occure in XBMC.

I also try following code but it not work

System.Diagnostics.Process[] xbmc = System.Diagnostics.Process.GetProcessesByName("XBMC");
IntPtr hWnd = xbmc[0].MainWindowHandle;
ShowWindow(hWnd,0);

this.FormBorderStype = ForeBorderStype.None;
this.WindowState = FormWindowState.Maximized;
this.BringToFront();

Any one can help , How to set my app to run as foreground over XBMC.

Thank.