Some questions about Wayland

Pekka Paalanen ppaalanen at
Wed Apr 11 01:16:32 PDT 2012

On Wed, 11 Apr 2012 09:51:22 +0200
Renaud Hebert <renozyx at> wrote:

> Hello,
> In the comments on an article about "the state of Wayland" at lwn
> (, two interesting questions were
> raised:
> 1- would gridmgr (an application which place the windows into
> predefined grid layouts ) work on Wayland?
> 2- same question for Gromit
> ( an application which allow
> you to "draw" on your screen.
> For (1), I think that this would require an extension specific to the
> compositor used (Weston, KDE's planned compositor, etc).

Yes, because that is a window manager's job and requires knowledge of
all windows on screen. Most likely it would be implemented in the
server and only controlled by a special client.

In X any application can walk over your window manager and fight with
it, in Wayland such is not possible and clients cannot know about other
clients' windows, and not even about absolute window positions.

> For (2), I don't know: I think that this would require some form of
> input redirection (there would be a fullscreen transparent windows but
> when not in drawing mode it shouldn't receive the mouse events) and I
> don't think that Wayland has this feature?

That's easy: Wayland surfaces have an input region, and that region can
be empty. Only input region receives input events, regardless of (well,
clipped to, really) the surface size. So you just make your maximised
transparent window and set the input region to empty, and all pointer
and touch events will bypass your window. When you want to draw, make
that input region non-empty. You probably need another window to click
at for that. ;-)


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