Many thanks for your answer. I have tried to achive it according to this tutorial: 
http://withinrafael.com/adding-the-aero ... s-10-apps/I replaced 
Code:
var windowHelper = new WindowInteropHelper(this);
 to the taskbar hwnd 
Code:
IntPtr hWndTray = FindWindow("Shell_TrayWnd", null);
 and the SetWindowCompositionAttribute function: 
Code:
SetWindowCompositionAttribute(hWndTray, ref data);
It works but when I open the default windows startmenu or startscreen (click to the startbutton) then the changes will lost.
I don't know how to persist the changes :-/