[PATCH wayland 2/2] protocol: Add DnD actions

[Michal Suchanek]

Hello,

On 14 January 2016 at 13:51, Jonas Ådahl <jadahl at gmail.com> wrote:
> On Thu, Jan 14, 2016 at 11:50:29AM +0100, Michal Suchanek wrote:
>> On 14 January 2016 at 01:54, Carlos Garnacho <carlosg at gnome.org> wrote:
>> > Hi Michal,
>> >

>> > have you
>> > considered compatibility with Xdnd?
>>
>> As compatibility with X is always best effort so long as something can
>> be transferred it's probably ok.
>
> No, "best effort" is not Ok. Compatibility with XDND means compatibility
> with the rest of the whole world for probably quite some time. Part of
> the reason why the current proposal looks like it does is for making it
> possible to interoperate with XDND via Xwayland.
>
> You seem to mostly care about use cases where the applications use
> special modifier or button combinations to change the mime-type that is
> transfered. This something the current additions doesn't support, since
> it is the compositor that takes the input grab during the grab and we
> don't introduce any new modifier events anywhere. This, however, doesn't
> mean it is impossible to introduce modifier events in some way in the
> future.
>
>>
>> > This all was already discussed in
>> > ealier threads with no clear gains on either other option. And being
>> > at v9 of this patch, I'm not personally keen on modifying such
>> > fundamental aspect.
>> >
>>
>>
>> Without that I doubt many people will be keen on using it.
>
> On the contrary, these improvements already make it possible for the
> majority of DnD clients to start working properly. It's a step in the
> right direction, but to start supporting every thinkable use case from
> the beginning, before we actually have real world examples of how it
> should actually work is risky business, and that is not the intention of
> the discussed patches.
>
>

Ok, so I give you some very practical example.

On Windows the DnD convention is that Ctrl triggers copy action, Shift
triggers move and Ctrl+Shift triggers ask.

Now if I wanted to implement Windows feel-alike client so users can
easily use the interface they are accustomed to I would have to add
the Ctrl+Shift binding which is *not* possible.

On a Mac the modifiers are different. IIRC it pretty much uses the
Windows key everywhere a PC uses the Control key for keyboard
shortcuts. So for Mac feel-alike application I need to remap the
modifiers.

The hypothetical example with Alt and 10th mouse button is not
completely made up - many applications use configureble key bindings
to boost productivity of often used functions. With inability to
modify the DnD action with custom modifiers in either client the
options are severely limited here. Sure, one can use the primary
selection instead if it ends up allowing custom paste keybindings but
that's supposed to be experimental optional feature and not core part
of the protocol.

If you make the protocol so limited that the whole thing is
best-effort then sure the XDND translation can be 100%. I am not sure
that should be the goal here, though.

Thanks

Michal