244c266c9f
Not checking for this would result in `clutter_actor_add_child`
failing, but StBin keeping a copy in `priv->child`. So later on,
`st_bin_remove` would never be called on it and this assertion
would fail and crash the whole shell:
```
static void
st_bin_destroy (ClutterActor *actor)
{
StBinPrivate *priv = st_bin_get_instance_private (ST_BIN (actor));
if (priv->child)
clutter_actor_destroy (priv->child);
g_assert (priv->child == NULL);
```
By disallowing spurious `st_bin_set_child` calls we now prevent StBin
from entering such a corrupt state and the above assertion won't fail
anymore.
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1507>
GNOME Shell
GNOME Shell provides core user interface functions for the GNOME 3 desktop, like switching to windows and launching applications. GNOME Shell takes advantage of the capabilities of modern graphics hardware and introduces innovative user interface concepts to provide a visually attractive and easy to use experience.
For more information about GNOME Shell, including instructions on how to build GNOME Shell from source and how to get involved with the project, see the project wiki.
Bugs should be reported to the GNOME bug tracking system.
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To contribute, open merge requests at https://gitlab.gnome.org/GNOME/gnome-shell.
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License
GNOME Shell is distributed under the terms of the GNU General Public License, version 2 or later. See the COPYING file for details.