Re: [EWMH] _NET_WM_WINDOW_TYPE_AUXILIARY

On Wednesday 03 of October 2007, Havoc Pennington wrote:
> Hi,
>
> On 10/3/07, Denis Washington <[email protected]> wrote:
> > Yes, override-redirect windows are also faded in and out
>
> Right, what I'm asking is whether we have any precedent for *hints* on
> these windows.

 Yes, right in the spec, since some time :). There's e.g. a short 
section "Override-redirect windows" mentioning them.

> It's kind of a weird thing, because override redirect has always been
> the "don't mess with my window at all" escape hatch. Metacity for
> example won't even create an inside-WM representation for these
> windows.
>
> For compositing managers, I guess if it didn't mess with your window
> at all then the window wouldn't be drawn on the screen. But I'm
> wondering to what extent the escape hatch still exists. Do we have in
> the EMWH these days something like "override redirect causes the WM to
> ignore a window for purposes of resizing, stacking, and window
> navigation; however, override redirect has no effect on compositing
> the window"?

 No, there's nothing like that in the spec, but it's kind of logical that a WM 
wouldn't resize or Alt+Tab to an override-redirect window. However, in fact, 
probably having something like that stated explicitly would be against the 
usual spirit of X of not forbidding anything just in case one day somebody 
comes up with a way of doing it that makes sense ;).

> Anyway - regarding the hint proposal, one suggestion is to come up
> with a more descriptive name than AUXILIARY, such as VISUAL_EFFECT.
> Then in defining what the WM should do with this window, spell out
> that the CM should render the window "as is" - which is almost saying
> "do the equivalent of override redirect for compositing, since
> override redirect itself does not apply to compositing" - that is,
> composite this window literally without overriding anything. I don't
> know. Anyway, it needs to be precisely specified what you want the CM
> to do and not do.

 I agree here. AUXILIARY sounds like A_SPECIAL_HACK. I think that ideally all 
such effects should be in the CM, but in reality I would be fine with having 
this VISUAL_EFFECT.

> I'm not sure whether out-of-CM effects like this really work... it
> seems possible to me that fancy effects spanning multiple X clients
> essentially have to be in the CM.
> Depends on whether you can adequately specify what an arbitrary CM
> should do with the window here.
>
> I'm sure someone who hacks on CMs will be able to address your
> proposal better than I can ;-)

-- 
Lubos Lunak
KDE developer
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