bug#71656: secondary selection and mouse-drag-secondary-pasting is broken in 29.3 under wayland

bug#71656: secondary selection and mouse-drag-secondary-pasting is broken in 29.3 under wayland

[John Heidemann]

Since Fedora 40 and emacs-29.3, mouse-drag-secondary-pasting has thrown
the error "Could not assert ownership over selection: SECONDARY".

This is in a default Fedora 40 install with the emacs-29.3-6.fc40.x86_64
package, running under Wayland.  I think F40 started using native
wayland and gtk, which perhaps lost support for secondary selections?


To reproduce:

start emacs -q

In *scratch* run:

(require 'mouse-copy)
(global-set-key [M-down-mouse-1] 'mouse-drag-secondary-pasting)

Then hold down meta and right click and drag over a word.

Expected behavior:

The text you drag over should be copied to the current location.

Actual behavior:
error "Could not assert ownership over selection: SECONDARY"
and no copying happens.


I was the original author of mouse-copy.el and I miss its easy
plan-9-like copy what I just moused over.

I'm happy to patch its code, but I'd like to know what changed so I can
know what I need to work around.


Thanks for any pointers,
   -John Heidemannp

bug#71656: secondary selection and mouse-drag-secondary-pasting is broken in 29.3 under wayland

[Eli Zaretskii]

> From: John Heidemann <johnh@isi.edu>
> Date: Wed, 19 Jun 2024 12:33:04 -0700
> 
> Since Fedora 40 and emacs-29.3, mouse-drag-secondary-pasting has thrown
> the error "Could not assert ownership over selection: SECONDARY".
> 
> This is in a default Fedora 40 install with the emacs-29.3-6.fc40.x86_64
> package, running under Wayland.  I think F40 started using native
> wayland and gtk, which perhaps lost support for secondary selections?
> 
> 
> To reproduce:
> 
> start emacs -q
> 
> In *scratch* run:
> 
> (require 'mouse-copy)
> (global-set-key [M-down-mouse-1] 'mouse-drag-secondary-pasting)
> 
> Then hold down meta and right click and drag over a word.
> 
> Expected behavior:
> 
> The text you drag over should be copied to the current location.
> 
> Actual behavior:
> error "Could not assert ownership over selection: SECONDARY"
> and no copying happens.
> 
> 
> I was the original author of mouse-copy.el and I miss its easy
> plan-9-like copy what I just moused over.
> 
> I'm happy to patch its code, but I'd like to know what changed so I can
> know what I need to work around.
> 
> 
> Thanks for any pointers,

Thanks.  Po Lu, can you please look into and fix this, or help John
fix it?

bug#71656: secondary selection and mouse-drag-secondary-pasting is broken in 29.3 under wayland

[Po Lu via Bug reports for GNU Emacs, the Swiss army knife of text editors]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: John Heidemann <johnh@isi.edu>
>> Date: Wed, 19 Jun 2024 12:33:04 -0700
>> 
>> Since Fedora 40 and emacs-29.3, mouse-drag-secondary-pasting has thrown
>> the error "Could not assert ownership over selection: SECONDARY".
>> 
>> This is in a default Fedora 40 install with the emacs-29.3-6.fc40.x86_64
>> package, running under Wayland.  I think F40 started using native
>> wayland and gtk, which perhaps lost support for secondary selections?
>> 
>> 
>> To reproduce:
>> 
>> start emacs -q
>> 
>> In *scratch* run:
>> 
>> (require 'mouse-copy)
>> (global-set-key [M-down-mouse-1] 'mouse-drag-secondary-pasting)
>> 
>> Then hold down meta and right click and drag over a word.
>> 
>> Expected behavior:
>> 
>> The text you drag over should be copied to the current location.
>> 
>> Actual behavior:
>> error "Could not assert ownership over selection: SECONDARY"
>> and no copying happens.
>> 
>> 
>> I was the original author of mouse-copy.el and I miss its easy
>> plan-9-like copy what I just moused over.
>> 
>> I'm happy to patch its code, but I'd like to know what changed so I can
>> know what I need to work around.
>> 
>> 
>> Thanks for any pointers,
>
> Thanks.  Po Lu, can you please look into and fix this, or help John
> fix it?

John, this error is signaled when the SECONDARY selection is not
implemented by your Wayland compositor.  I don't believe this is any
responsibility of ours, and hence your Lisp code should resort to a
different selection on PGTK systems.

bug#71656: secondary selection and mouse-drag-secondary-pasting is broken in 29.3 under wayland

[John Heidemann]

On Thu, 20 Jun 2024 14:39:28 +0800, Po Lu wrote: 
>Eli Zaretskii <eliz@gnu.org> writes:
>
>>> From: John Heidemann <johnh@isi.edu>
>>> Date: Wed, 19 Jun 2024 12:33:04 -0700
>>> 
>>> Since Fedora 40 and emacs-29.3, mouse-drag-secondary-pasting has thrown
>>> the error "Could not assert ownership over selection: SECONDARY".
>>> 
>>> This is in a default Fedora 40 install with the emacs-29.3-6.fc40.x86_64
>>> package, running under Wayland.  I think F40 started using native
>>> wayland and gtk, which perhaps lost support for secondary selections?
>>> 
>>> 
>>> To reproduce:
>>> 
>>> start emacs -q
>>> 
>>> In *scratch* run:
>>> 
>>> (require 'mouse-copy)
>>> (global-set-key [M-down-mouse-1] 'mouse-drag-secondary-pasting)
>>> 
>>> Then hold down meta and right click and drag over a word.
>>> 
>>> Expected behavior:
>>> 
>>> The text you drag over should be copied to the current location.
>>> 
>>> Actual behavior:
>>> error "Could not assert ownership over selection: SECONDARY"
>>> and no copying happens.
>>> 
>>> 
>>> I was the original author of mouse-copy.el and I miss its easy
>>> plan-9-like copy what I just moused over.
>>> 
>>> I'm happy to patch its code, but I'd like to know what changed so I can
>>> know what I need to work around.
>>> 
>>> 
>>> Thanks for any pointers,
>>
>> Thanks.  Po Lu, can you please look into and fix this, or help John
>> fix it?
>
>John, this error is signaled when the SECONDARY selection is not
>implemented by your Wayland compositor.  I don't believe this is any
>responsibility of ours, and hence your Lisp code should resort to a
>different selection on PGTK systems.

Thank you.  It looks like large parts of mouse.el (all the functions
ending in -secondary) and select.el are X11-specific then and will not
work on Wayland.

It looks like there is already some work in select.el to make it ignore
primary/secondary/clipboard for windows.  Perhaps analogous code needs
to go in to Wayland, so that downstream code (such as mouse.el and
mouse-copy.el) would continue to work?

   -John

bug#71656: secondary selection and mouse-drag-secondary-pasting is broken in 29.3 under wayland

[Po Lu via Bug reports for GNU Emacs, the Swiss army knife of text editors]

John Heidemann <johnh@isi.edu> writes:

> Perhaps analogous code needs to go in to implementing that downstream
> code (such as mouse.el and mouse-copy.el) would continue to work?
>
>    -John

Patches welcome, as ever.  One difficulty I anticipate is that some GDK
backends and Wayland compositors do support SECONDARY, while one Emacs
session is capable of being connected to multiple displays providing
different repertories of selections, and even potentially implemented by
multiple GDK backends.  Another is that the existence of support for a
selection cannot be ascertained until an attempt is made to acquire
ownership of it.