Re: emacs24 X primary selection changes

[Jason Rumney <jasonrumney@gmail.com>]

On Saturday, 5 January 2013 07:11:43 UTC+8, Bob Proulx  wrote:

> But X Window applications have always expected dragging mouse-1 to
> copy text and mouse-2 to paste text.

Which is what Emacs has always, and still does.

> I am becoming more convinced that it is a poor description.  But that
> modifying word "modern" is a "weasel word" that makes it harder to
> nail down.  It allows for "modern X app" to be different from "X app".
> If modern X applications are becoming more MS Windows like then it is
> true even if it is less X Window like.

Modern X applications are not becoming less X Window like.  In the bad old days, you had applications like xterm that only supported PRIMARY, and other applications (CDE ones especially, probably also Motif where they came from) that only supported CLIPBOARD.  There was no standard, and Emacs way of doing things was only one of many.

Now things are standardising - PRIMARY is for the currently selected text, and CLIPBOARD is for text that you explicitly put there.  It has been that way in Emacs for some time, except that the Emacs kill-ring (C-w/M-w/C-y) put PRIMARY are the front of the kill-ring, even though use of the kill-ring is an explicit action, so fits better with the CLIPBOARD.

In summary:

Selecting text with the mouse or keyboard: puts the text in PRIMARY for as long as the selection remains active and some other application does not override it.  In earlier versions, the text could remain in PRIMARY even after the selection became inactive.

mouse-2: inserts the text from PRIMARY (in previous versions it inserted from the kill-ring, which was often the same thing due to Emacs putting PRIMARY at the head of the kill-ring).

C-y: inserts the text from the kill-ring. In Emacs-24, CLIPBOARD from other applications is automatically placed at the head of the kill-ring, in previous versions, PRIMARY from other applications is automatically placed at the head of the kill-ring.

C-w/M-w: kill/copy to the kill-ring.  In Emacs-24, these also put text on the CLIPBOARD for other applications. In earlier versions, they put non-selected text into PRIMARY (which is non-standard behaviour - I don't think any other X application does/did this).