Hiding the whole GUI?

[blablub]

Hi,

is there a way to hide (and later show again) the whole GUI?

Something like this?
CEGUI::System::getSingleton().renderGUI(false);

I can't just hide the root DefaultWindow from the layout. Problem is: If someone changes the name of it, I had to change the source code, because the Windows are accessed by its names (then the Window->hide() wouldn't work anymore because the Windows name doesn't exist anymore). I also have more than one Layout, where the root DefaultWindow have different names -> same problem.

[Kulik]

CEGUI::System::getSingleton().getGUISheet()->hide() ?
and ->show() of course