bug#6637: 24.0.50; kill ring being seriously polluted

[Chong Yidong]

Tim Van Holder <tim.vanholder@gmail.com> writes:

> 1) emacs -Q
> 2) Holding the shift key, press the up arrow until you're at the top
> of the buffer
> 3) Release the shift key and press the down arrow until you're back at
> the bottom of the buffer
> 4) Press C-y
>
> This yanks in the comment lines, even though I at no point requested a
> kill or copy-as-kill.

Go to any X application (firefox, etc) with a text field.
Holding shift, press the arrow keys and select some text.
Release shift, and press another down arrow to deselect it.

In Emacs 23 (in the absence of latest changes):

Run `emacs -Q'.
C-y

The text you selected is yanked into the buffer.  This is because the
other X application put your selected text in the primary selection.
How is the behavior of Emacs' new shift selection different from the
other X application's shift selection?