I use Ubuntu 12.04 (Unity). How would I do that when I pressed the close button to Minimize the window, as is the case with Mac OS. The program is closed but is still running in memory until it is completely closed by right-clicking and Quit. This would be particularly useful especially for programs such as Thunderbird and various Twitter clients. P.S. Sorry for my bad english.
A simple trick that I use when I want to have a program running, but out of sight, it is sending it to another workspace. I usually use two workspaces, one for the programs that I'm working on and another one for the "sleepers".