Fix bug #7196.

 NEWS: Expand the entry about "Selection changes".

etc/NEWS

@@ -230,22 +230,62 @@ should use delete-char with a negative argument instead.
 The default handling of clipboard and primary selections has been
 changed to conform with other X applications.
 
+The new behavior is that by default Emacs does not put text into the
+clipboard, and does not add it to kill-ring, merely because the text
+was selected.  Only commands that kill text or copy it to the
+kill-ring (C-w, M-w, C-k, etc.) put the killed text into the
+clipboard.  Selected text is put into the primary selection (on
+systems, such as X, that support the primary selection separately from
+the clipboard).
+
+Similarly, Emacs by default does not retrieve text from the clipboard
+when the mouse (e.g., mouse-2) is used for pasting text selected in
+another application.  Text from the clipboard is retrieved only by
+C-y, M-y and other commands that yank text from the kill-ring.  Mouse
+commands that paste text retrieve text from the primary selection, on
+systems that support it separately from the clipboard.
+
+In other words, the default behavior is that mouse gestures that
+select and paste text work with the primary selection, while keyboard
+commands that kill/copy and paste text work with the clipboard.
+
+This change also means that the "Copy", "Cut", and "Paste" items of
+the menu-bar "Edit" menu are now exactly equivalent to, respectively
+M-w, C-w, and C-y.
+
+To get back the previous behavior, whereby mouse gestures set the
+clipboard and retrieve text from there, customize the variables
+`mouse-drag-copy-region' and (on X only) `x-select-enable-primary'.
+If you don't want Emacs to put the text into the clipboard, only to
+the primary selection, additionally customize
+`x-select-enable-clipboard' to nil.
+
+These changes in the default behavior are reflected in the default
+values of several variables:
+
 *** `select-active-regions' now defaults to t, so active regions set
-the primary selection.
+the primary selection.  It was nil in previous versions.
 
 It also accepts a new value, `only', which means to only set the
 primary selection for temporarily active regions (usually made by
 mouse-dragging or shift-selection).
 
 *** `mouse-2' is now bound to `mouse-yank-primary'.
+Previously, it was bound to `mouse-yank-at-click' (which is now
+unbound by default.
 
-*** `x-select-enable-clipboard' now defaults to t.
+*** `x-select-enable-clipboard' now defaults to t on all platforms.
 Thus, killing and yanking now use the clipboard (in addition to the
-kill ring).
+kill ring).  Note that this variable was already non-nil by default on
+MS-Windows, which does not support the primary selection between
+applications.
 
 *** `x-select-enable-primary' now defaults to nil.
+This variable exists only on X; its default value was t in previous
+versions.
 
 *** `mouse-drag-copy-region' now defaults to nil.
+Its previous default value was t.
 
 *** Support for X cut buffers has been removed.