How to make your Ubuntu use "clone" screen, when I input projector? It always go to extended desktop and then I need to check "clone screen" and apply. How to make it remember I always want to "clone"? I am using ATI open-source drivers.
I don't think there's really a way to do that. Of course, having options is always nice, but in my experience such an option isn't really desirable, anyway.
The trouble is that these days, most laptops have wide screens--with varying aspect ratios--while projectors still prefer 1024x768 (4:3). If you clone the screen, you're going to get a stretched and/or low quality picture on one or both screens unless the projector knows how to compensate.
Using Ubuntu's default makes it possible for everything to look good, even if you have to manually set the resolution if you're using certain hardware. (The two projectors I regularly use don't adequately report their preferred resolution, leaving me with a stretched display until I manually correct it, while the TV I've been using recently in lieu of one of the projectors manages to get everything automatically configured correctly.)
Finally, I don't think there's any real advantage to having a cloned screen. OpenOffice automatically shows presentations on the correct screen, assuming that the screen is connected and enabled when the program starts. Other windows can easily be dragged to the proper screen. Then, they'll behave correctly. And, you don't have to worry about things like your panels and icons showing up on the big screen.