Bug#925581: impossible to scroll in mate-panel

[DC-1]

Package: libgtk-3-0
Version: 3.24.5-1

It's impossible to select new keyboard layout, due to can't scroll in
mate-keyboard-preferences .

It is a known bug discussed at:
https://github.com/mate-desktop/mate-panel/issues/920

The bug was fixed in gtk 3.24.6 with this patch:
https://gitlab.gnome.org/GNOME/gtk/commit/1d4eac211c09624d29b9309e2b92173f7477a9b7


Please backport this patch for 3.24.5 before first Buster release.