User is unable to create custom desktop background (wallpaper) slide show or edit the settings of existing

[Norbert]

#### Steps to reproduce the behaviour
1. Have Ubuntu MATE 19.10 installed
2. Use right mouse click on the *Desktop* to select *Change Desktop Background* (or run `mate-appearance-properties --show-page=background` directly)
3a. Try to edit settings of existing Cosmos (images are located in `/usr/share/backgrounds/cosmos` and configured by `/usr/share/backgrounds/cosmos/background-1.xml` file) slide show.
3b. Try to create new slide show of user-defined folder with images

#### Expected behaviour
a. User is able to change setting of existing slide show
b. User is able to create new slide show

#### Actual behaviour
a. User is unable to change setting of existing slide show
b. User is unable to create new slide show

#### MATE general version
MATE 1.22.2

#### Package version
1.22.2-0ubuntu3

#### Linux Distribution
Ubuntu MATE 19.10

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Notes: previously it was reported upstream for Caja package (see https://github.com/mate-desktop/caja/issues/1052 ).

ProblemType: Bug
DistroRelease: Ubuntu 19.10
Package: mate-control-center 1.22.2-0ubuntu3
ProcVersionSignature: Ubuntu 5.3.0-18.19-generic 5.3.1
Uname: Linux 5.3.0-18-generic x86_64
ApportVersion: 2.20.11-0ubuntu8
Architecture: amd64
CurrentDesktop: MATE
Date: Sun Dec 8 15:41:45 2019
InstallationDate: Installed on 2019-10-19 (50 days ago)
InstallationMedia: Ubuntu-MATE 19.10 "Eoan Ermine" - Release amd64 (20191017)
SourcePackage: mate-control-center
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

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

[Norbert (nrbrtx)]

Bug still exists in latest Ubuntu MATE 22.04 LTS.