I have installed Ubuntu Gnome 14.04

The problem is :

Nautilus(I think it called "Files" in gnome-shell) has no Minimize/Maximize button !

I have enabled `gnome-tweak-tool -> Windows -> Maximized/Minimized`, but Nautilus has not Minimize/Maximize buttons!

![enter image description here](https://i.stack.imgur.com/vYhxC.png)

Any ideas?