There is also the sudo configuration file, where you can allow applications to be started without password-query. How to use it, is described here: http://www.gratisoft.us/sudo/man/1.8.0/sudoers.man.html
Warning: Though very unlikely, messing with sudoers configuration could lock you out of your system or open doors for others. Always double check and be sure of what you're doing.
As a safety precaution you can open a root shell and keep it open until you have tested your changes. Open a shell and type
sudo su, you will be asked for your password. Your shell is now a root shell. Also you can make a backup of your
/etc/sudoers file to be able revert changes.
The basic use is you edit it by invoking visudo in shell:
sudo select-editor # this is optional. it will allow you to select your default editor in shell
The latter of wich will open your shell default editor with the file. Normal syntax is:
username machine=(usernameToRunCommandAs) command1,command2,...
confus confusion=(root) NOPASSWD:/sbin/halt,/sbin/reboot/usr/sbin/synaptic #allows user confus to run "sudo synaptic" as root on confusion without password querry
confus ALL=(ALL) NOPASSWD:/sbin/halt,/sbin/reboot #allows confus to shutdown and reboot as all users on all machines without pw
$PATH variable is user dependent and sudo is not, the full path to the command is needed in sodoers list (note it says '/sbin/halt' not just 'halt'). You can find out the full path using the
whereis command - as in
whereis halt which will most likely return '/sbin/halt'.
Generelly speaking that's bad practise. You are asked for a reason. Installing software with synaptic ist potentially harmfull. As is tempering with partitions which can lead to an unbootable system and massive data loss. It also makes a hackers job much easier. But you're free to do it on your own risk.