[gnome-software/1420-app-page-show-more-button-label-glitches-while-resizing] Add a comment with a reference to a gtk+ merge request

[Milan Crha <mcrha src gnome org>]

commit 66b454456ff3cc750d252e4e3c0daa32fe6de16f
Author: Philip Withnall <philip tecnocode co uk>
Date:   Tue Sep 14 15:50:10 2021 +0000

    Add a comment with a reference to a gtk+ merge request

 src/gs-description-box.c | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/src/gs-description-box.c b/src/gs-description-box.c
index 6e942452b..5497693f5 100644
--- a/src/gs-description-box.c
+++ b/src/gs-description-box.c
@@ -63,6 +63,8 @@ gs_description_box_update_content (GsDescriptionBox *box)
        box->last_height = allocation.height;
 
        text = box->is_collapsed ? _("_Show More") : _("_Show Less");
+       /* FIXME: Work around a flickering issue in GTK:
+        * https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/3949 */
        if (g_strcmp0 (text, gtk_button_get_label (box->button)) != 0)
                gtk_button_set_label (box->button, text);