By default, double-click title-bar maximize Ubuntu 12.04′s window, middle-click lower current window and right-click launches window menu. If you wouldn’t like these window click activities, you can easily change them by Ubuntu configuration tool: gnome-tweak-tool or gconf-editor.

Gnome Tweak Tool can be installed by this command in terminal (Ctrl+Alt+T to launch terminal) or Software Center:

sudo apt-get install gnome-tweak-tool

Then launch Advance Settings, in Windows tab configure title bar click action.

gconf-editor can be installed by this command or Software Center:

sudo apt-get install gconf-editor

Launch gconf-editor (configuration editor), navigate to apps -> metacity -> general. Configure the title bar action from: