xdg-desktop-portal-gtk malfunctions on Wayland: [e-mail](zxdg_imported_v1@36, 0, "set_parent_of was called with an invalid child")

[James Henstridge]

When running on a Wayland session, if xdg-desktop-portal-gtk is asked to display a window on behalf of a Wayland app, it gets disconnected from gnome-shell with one of these messages:

    Gdk-Message: 09:49:31.837: Lost connection to Wayland compositor.
    Gdk-Message: 09:50:28.438: Error 71 (Protocol error) dispatching to Wayland display.

Running it with WAYLAND_DEBUG=1, the underlying error message that GDK seems to eat is:

    [3471970.531] [e-mail](zxdg_imported_v1@36, 0, "set_parent_of was called with an invalid child")

That is, when it tries to associate the dialog box with the confined application's window. It seems the underlying bug is in in Mutter:

    https://gitlab.gnome.org/GNOME/mutter/issues/138

According to duflu, the patch referenced in that bug report has been merged for 3.28.2 and 3.29.2. It seems like a candidate to backport to bionic if we want portals to work on the (non-default) Wayland session.

[Daniel van Vugt (vanvugt)]

Yeah cosmic already has the fix (mutter 3.28.2). You're only waiting on bionic.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Michael Gratton (mjog)]

It would be great to get the fix backported to Bionic since people have been reporting this as bug in Geary already: https://bugzilla.gnome.org/show_bug.cgi?id=789846#c6

[James Henstridge (jamesh)]

bionic-proposed has a 3.28.2 package, so this should be resolved for that release shortly.

[Andrew Hayzen (ahayzen)]

Is this a bug in mutter that has been fixed ? As I'm wondering why this bug is still open for xdg-desktop-portal-gtk and if it can be closed ?