seprate window management component

Sam Spilsbury smspillaz at
Thu Sep 15 18:07:39 PDT 2011

On Wed, Sep 14, 2011 at 11:19 PM, Michal Suchanek <hramrach at> wrote:
> Hello,
> On 14 September 2011 16:55, cat <zixon65 at> wrote:
>> would it be to much trouble to make window management a proxy program?
> The wayland server has to know how the windows stack but the clients
> are not trusted to tell it how the windows should stack so either the
> server has to figure that out by itself or a separate privileged
> component (eg. a proxy or a plugin or attached process of some sort)
> would need to decide that.
> I thought that it would make sense to determine what policy needs to
> be decided by this manager and add protocol for it in Wayland even if
> the default implementation will just grant every request an
> application ever makes.
> When I asked about that it was not outright rejected but there was
> nobody else who though putting some structure into Wayland would be of
> any use.
> I guess this will be considered only after Wayland evolves so many
> warts as X has and putting some sanity in the protocol will be
> impossible at that point for reasons of backward compatibility and
> whatnot.

The biggest problem with the X protocol is that you talk to the window
manager by making requests to the server and having them redirected by
the window manager. Then the window manager being "priviledged" for
that window (see SubstructureRedirectMask) is able to make requests to
the server and have them be processed without redirect. This approach
is somewhat inflexible and brings problems with eg, override redirect
windows and out-of-order bugs when processing ConfigureRequests for
normal windows and only receiving a ConfigureNotify for override
redirect windows.

In any case, the protocol for talking to the window manager should be
part of a separate API that functions outside of the compositor. I
think whether or not this is done out of process or in process is
simply a matter of implementation.

(In this process at least, all window management related requests
would go through the window management policy first, rather than
having the situation where we do now where the window manager must
process requests after the fact in some cases)


> Thanks
> Michal
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> wayland-devel at

Sam Spilsbury

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