Re: Selection changes in revno 100822

[David De La Harpe Golden]

On 15/08/10 15:04, Stephen J. Turnbull wrote:

> If you want X11 and Windows (and Mac, for that matter) to have similar
> interfaces here, then you could disable middle-click-to-paste (by
> default) on X11, and use "drag to paste" consistently.
>
> Of course wizened (or seasoned) X users probably would want to
> reenable middle click to paste.

In practice, on x11, the drag/drop you describe typically coexists 
happily with middle-click-paste-selection.

While the w32 text drag and drop is indeed a bit more like an x11 
primary than the w32 clipboard is in terms of effect and purpose, in 
actual implementation terms on x11, 'XdndSelection and 'PRIMARY are 
again different x11 selections (former is already handled somewhat by 
x11 emacs* lisp/x-dnd.el, though x11 emacs doesn't appear to allow 
intra-emacs text drag/drop, it does appear to accept text dragged into 
it), so there is an analog of the w32 drag/drop on x11 and it's the x11 
drag/drop rather than x11 primary as such.

Mind you, the XDND spec does then go on to suggest as an extension 
making allowance for older apps that don't support XDND (citing emacs as 
an example, I guess wouldn't have at the time it was written) by 
simulating a middle click into them on the assumption they will try to 
yank primary when they see the simulated middle click, and responding to 
the ensuing matched (via known timestamps) request for the primary as if 
it was request for the XdndSelection. Which is a bit of a bodge, I don't 
presently know if dnd-source x11 apps in the wild typically implement 
that bit.

It is likely possible to reuse various w32 bits and pieces (actually in 
the rat's nest of w32 apis there's probably quite a few different ways) 
to produce a w32 primary-oid that works inter-application for 
applications that know to look for it (presumably other emacs sessions).


[* Actually there's more than one protocol for DnD on x11, just to 
complicate matters, but x11 emacs also supports the motif one]