By default, the Mac will minimize a window if you double click on the title bar of the window. If you want to change the behavior so that it no longer minimizes the window when you click on it, you can change this behavior. Go to System Preference and select the Appearance (it's the first option in the Personal section) option. In there you will see a checkbox with the text "Minimize when double-clickin a window title bar". If you uncheck that box, it will no longer minimize the window when you double click on the title bar.