save-interprogram-paste-before-kill

save-interprogram-paste-before-kill is a variable defined in `simple.el'.
Its value is

nil

Documentation:
Save clipboard strings into kill ring before replacing them.
When one selects something in another program to paste it into Emacs,
but kills something in Emacs before actually pasting it,
this selection is gone unless this variable is non-nil,
in which case the other program's selection is saved in the `kill-ring'
before the Emacs kill and one can still paste it using C-y M-y.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 23.2 of Emacs.