Is there any way to make programs ask for password when root is required? For example I want to extract some files with File Roller into /usr/share/ where apparently root is required but instead of the error that it gives me I would like a password prompt.
To directly answer your question: No, there is no way (as far as I am aware) to make a program to ask for a password instead of failing when it doesn't have enough permissions to perform an operation. There are two options:
Some programs are aware that they need administrative privileges for some operations and ask for a password before doing something (i.e. Software Center asks for a password before installing programs).
Most other programs need to be started with necessary privileges. As it has been mentioned, you need to use sudo [command] (in terminal), gksu [command] (in Gnome/Unity) or kdesu [command] (in KDE) for that.
