というわけで Emacs 24 に晴れてバージョンアップすることになった．

M-; emacs-version
=> "24.3.1"

一応そんなに破壊的な変更は無いと見ていたし，実際ほとんど .emacs に変更は必要なかったが，X 周りは若干変わった点があったので注意が必要．

自分で今までに気づいた変更はクリップボードとの連携がうまくいかなくなったこと．NEWS.24.1 に記述があって，従来の挙動に戻す方法も書いてあるのでそれに倣えば OK.

** Selection changes.

The default handling of clipboard and primary selections has been changed to conform with modern X applications. In short, most commands for killing and yanking text now use the clipboard, while mouse commands use the primary selection.

In the following, we provide a list of these changes, followed by a list of steps to get the old behavior back if you prefer that.

*** `select-active-regions’ now defaults to t. Merely selecting text (e.g. with drag-mouse-1) no longer puts it in the kill ring. The selected text is put in the primary selection, if the system possesses a separate primary selection facility (e.g. X).

**** select-active-regions' also accepts a new value, only’. This means to only set the primary selection for temporarily active regions (usually made by mouse-dragging or shift-selection); “ordinary” active regions, such as those made with C-SPC followed by point motion, do not alter the primary selection.

**** `mouse-drag-copy-region’ now defaults to nil.

*** mouse-2 is now bound to mouse-yank-primary'. This pastes from the primary selection, ignoring the kill-ring. Previously, mouse-2 was bound to mouse-yank-at-click’.

*** `x-select-enable-clipboard’ now defaults to t on all platforms.

*** `x-select-enable-primary’ now defaults to nil. Thus, commands that kill text or copy it to the kill-ring (such as M-w, C-w, and C-k) also use the clipboard—not the primary selection.

**** The “Copy”, “Cut”, and “Paste” items in the “Edit” menu are now exactly equivalent to M-w, C-w, and C-y respectively.

**** Note that on MS-Windows, `x-select-enable-clipboard’ was already non-nil by default, as Windows does not support the primary selection between applications.

*** To return to the previous behavior, do the following:

**** Change select-active-regions' to nil. **** Change mouse-drag-copy-region’ to t. **** Change x-select-enable-primary' to t (on X only). **** Change x-select-enable-clipboard’ to nil. **** Bind `mouse-yank-at-click’ to mouse-2.