Re: Unexpected visual effect under GNOME Shell

[Michael Thayer <michael thayer oracle com>]

Hello Jonas,

Thank you, that does look like it.  I will tag onto that bug and see
what comes of it.

Regards
Michael

07.02.2018 04:21, Jonas Ådahl wrote:
> The flashing black rectangle you are seeing could possibly be
> https://bugzilla.gnome.org/show_bug.cgi?id=767212.
>
>
> Jonas
>
> On Tue, Feb 06, 2018 at 04:16:51PM +0100, Michael Thayer wrote:
> > Hello,
> >
> > Wondering if anyone can help us with the following question.  In
> > VirtualBox we need for various reasons to know what the usable area of
> > each screen is - that translates as the largest rectangle which fits on
> > that screen without obscuring any panels or similar.  We find that out
> > by mapping a maximised window on each screen at start-up and checking
> > its position and dimensions.  To prevent disturbance to the user we
> > create the window fully translucent, or if the X server does not support
> > that we use XShape and leave only a single pixel visible.  On GNOME
> > Shell Wayland edition (what is the right way to say that?) this
> > unfortunately flashes a black rectangle up on the screen in the area
> > which should be translucent.  I assume this is Xwayland-related, but is
> > there any way to prevent it?
> >
> > For a bit of background, creating a maximised window as we do was the
> > best way we found of getting the information we need.  Qt does not
> > provide it directly, _NET_WORKAREA is not quite the right thing either
> > and not all window managers provide usable strut information as some of
> > them composite panels directly rather than creating windows for them.
> > We use the area found for a number of things, in particular: adjusting
> > the size and position of windows restored from previous sessions if the
> > old positions no longer fit the current layout (especially to prevent
> > windows appearing off-screen) and correctly placing the toolbar windows
> > which we use in seamless mode, which we want to span the bottom
> > (usually) of a given screen, but above any window manager toolbars or
> > panels.  Of course, the problem is finding something which works, if not
> > in all window managers, at least for as many popular ones as possible.
> >
> > Thanks!
> > Regards
> > Michael
> > -- 
> > Michael Thayer | VirtualBox engineer
> > ORACLE Deutschland B.V. & Co. KG | Werkstr. 24 | D-71384 Weinstadt
> >
> > ORACLE Deutschland B.V. & Co. KG
> > Hauptverwaltung: Riesstraße 25, D-80992 München
> > Registergericht: Amtsgericht München, HRA 95603
> >
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> > der Handelskammer Midden-Nederland, Nr. 30143697
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> > _______________________________________________
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> > https://mail.gnome.org/mailman/listinfo/gnome-shell-list

-- 
Michael Thayer | VirtualBox engineer
ORACLE Deutschland B.V. & Co. KG | Werkstr. 24 | D-71384 Weinstadt

ORACLE Deutschland B.V. & Co. KG
Hauptverwaltung: Riesstraße 25, D-80992 München
Registergericht: Amtsgericht München, HRA 95603

Komplementärin: ORACLE Deutschland Verwaltung B.V.
Hertogswetering 163/167, 3543 AS Utrecht, Niederlande Handelsregister
der Handelskammer Midden-Nederland, Nr. 30143697
Geschäftsführer: Alexander van der Ven, Jan Schultheiss, Val Maher