[zzo38computer]

> Select to copy, middle-click to paste.

I also think that this is useful. Furthermore you can have separate selections: primary, secondary, and clipboard.

I use xterm, and shift+insert can also be used to paste from the primary selection. Firefox can copy to primary selection automatically and can paste by middle button, but shift+insert pastes from the clipboard instead; I think that it would be better for shift+insert to paste from primary selection and control+V (or command+V would be better; having that a separate key like Mac OS does is better, I think) for paste from clipboard.

Another thing that is helpful, but many modern programs do not do (some older programs do, such as Heirloom-mailx, and vi) that you can enter shell commands to be used by pipes to transfer data between programs (by use of popen function in C). (Some of my own programs have this capability)