bug#9623: mouse wheel scroll increases size of selected region

[Glenn Morris]

Package: emacs
Version: 24.0.90

In Emacs source directory:

./src/emacs -Q --eval '(transient-mark-mode -1)' ./README

With mouse, left-click on "S" in "See the end of the file for license
conditions.". Continue to hold button down, and drag to select the whole
of that sentence. Release mouse button. Do not make any more left clicks.
Using mouse wheel, scroll to end of buffer.
Left click to place point on last line.
Middle click to paste selected text. The text that gets pasted is larger
than what was selected. For me, the pasted text is

----
See the end of the file for license conditions.


This directory tree holds version 24.0.90 of GNU Emacs, the extensible,
-----

This seems to correspond to the region that scrolled off the screen the
first time I scrolled with the mouse wheel.

This does not happen in Emacs 23.3, which correctly pastes just the text
that was selected.

It also does not happen in 24.0.90 if I follow the advice from NEWS to
restore the old behaviour, namely:

(setq select-active-regions nil mouse-drag-copy-region t
      x-select-enable-primary t x-select-enable-clipboard nil)

So maybe it is intended? But it seems odd, so I am reporting it.