Thank you for the answer!
I already heard in the tiki irc channel, that bootstrap is just single level.
The problem i have with the superish css is, that i don't want the "drop-down", hover thingy. I want a normal menu, with collapses to the bottom. Like the folder-tree view in windows.
When i set bootstrap and css to n, than i have exakt that! But, i don't want the font awesome "warning" icon. I mean, why should someone want a warning in the navigation? It is not obvious, that you can click on it, so the menu will open, it's more like "uh... does the page exisist? is it under maintenance?"
What i need is the last option, but with something like the Caret Down Icon from Font Awesome. Is there a simple soluction to change what icons the menu uses?