Gnome Shell Extension Inhibit Applet is a gnome shell extension that gives you the ability to inhibit auto-suspend or screensaver from activating, simular to the original applet in gnome 2. It will add a new button on the panel with a dynamically changing icon to allow the user to see if the inhibit applet is active. Text describing the current state is shown on mouse hover.
Install it via extensions.gnome.org:
https://extensions.gnome.org/extension/233/inhibit-applet/
It's much easier than installing manually.
If you wish to install it manually, just copy the "inhibit-applet@alexjnewt.hotmail.com" folder into: ~/.local/share/gnome-shell/extensions
Copyright (C) 2012, Jeremy Newton
Copyright (C) 2011, Raphael Kimmig
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110, USA