Re: gEDA-user: [RFC 5/6] Use of X server clipboard

[Peter Clifton <pcjc2@xxxxxxxxx>]

On Sun, 2009-01-18 at 13:44 -0500, der Mouse wrote:
> >> I would actually recommend you use PRIMARY, not CLIPBOARD (though I
> >> also recognize that you may not have meant "clipboard" to be the
> >> technical term here).
> > No, Peter B and I discussed this, and we explicitly did _not_ want to
> > use PRIMARY.

The one thing that concerns me about the CLIPBOARD mechanism is that we
might not be able to export so many different types of data on it.

> Hm, then I suspect you'll find yourself unable to paste into X clients
> with relatively unsophisticated selection paradigms (which are likely
> to use PRIMARY and nothing else).

Realistically, I can't think what those clients might need to be.

The main use-cases we've envisaged are:

gschem-gschem windows
gschem->office application / presentation app / graphics editor
gschem->text editor (underlying text representation of the symbol /
schematic data)

All the text editors I use (emacs / gvim / ...) can paste text from the
CLIPBOARD, and Xterms can even paste text from the clipboard (I presume
they push it into the pty as if the user had typed it?).

> > The UI paradigm for PRIMARY is passing the currently selected text
> > between applications.
> 
> Well, the currently selected object.  Text is perhaps the commonest use
> of it, but it's by no means restricted to text.  But see below.
> 
> > If we start claiming the PRIMARY X selection every time someone has a
> > schematic object selected in gEDA, [...]
> 
> Oh, yes, certainly.  I wasn't thinking you'd take the selection every
> time an object is selected; I was expecting selecting as in picking an
> object to operate on and selecting as in preparing to paste would be
> different operations (with unfortunately similar names).

This isn't what many users will be used to in this day and age. Yes,
even I (a youngster) remember when X11 was focus follows mouse, and when
you really did have to mouse-over a text entry to type in it.. sadly a
lot of that is now lost. (Although I do set my WM to focus windows to
focus follows mouse, individual UI controls are still click-to-select).

I suppose we could use the PRIMARY selection for a Ctrl+C copy, but most
apps I've seen use select text -> PRIMARY, and Ctrl+C -> CLIPBOARD. (I
think).

I was also wondering if PRIMARY would be unsuitable, we could just
intern an atom for a "geda" selection, for pasting between gEDA apps
(assuming CLIPBOARD might not be flexible enough, and PRIMARY might want
to be reserved for selected text).

> > I don't know of any other applications which claim the PRIMARY
> > selection for graphical objects.
> 
> That's odd.  I don't see any basis in either the ICCCM or the EWMH for
> the use of anything else for routine selection data transport.  Is
> there something I missed, or is this just an observation that some
> client authors think they know better than the ICCCM spec that PRIMARY
> is "the principal means of communication between clients that use the
> selection mechanism"?

Most apps work fine, although I've noticed an irritating trend in Gnome
apps (The HTML viewing pieces?, as used in Epiphany / Firefox? /
Evolution mail client / devhelp), which _don't_ grab the PRIMARY
selection for selected text. That is _really_ infuriating.

I'm just observing that I've not seen any programs grab the PRIMARY
selection for graphical data.


-- 
Peter Clifton

Electrical Engineering Division,
Engineering Department,
University of Cambridge,
9, JJ Thomson Avenue,
Cambridge
CB3 0FA

Tel: +44 (0)7729 980173 - (No signal in the lab!)



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