Keyboard layout indicator on mate-panel does not update if user sets "while pressed" shortcut

[Norbert]

Steps to reproduce:
1. Install Ubuntu 16.04 LTS MATE or 18.04 LTS MATE
2. Add two keyboard layouts (for example, English and Russian)
3. Open `mate-keyboard-properties`
3.1. Click *Options*
3.2. In opened window expand *Switching to another layout*
4.4. Check checkbox named *Right Alt (while pressed)* (for example).
4.5. Close GNOME Tweaks windows
5. Test layout switching - press <RightAlt> and write some text

Expected results:
* keyboard layout indicator shows second keyboard layout when user holds <RightAlt> button and shows the first when it is not pressed

Actual results:
* keyboard layout indicator shows only the first keyboard layout

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: mate-settings-daemon 1.12.1-2build1
ProcVersionSignature: Ubuntu 4.4.0-128.154-generic 4.4.131
Uname: Linux 4.4.0-128-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.18
Architecture: amd64
CurrentDesktop: MATE
Date: Fri Jun 29 16:58:21 2018
InstallationDate: Installed on 2018-01-04 (175 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
SourcePackage: mate-settings-daemon
UpgradeStatus: No upgrade log present (probably fresh install)

[Norbert (nrbrtx)]

Can you reproduce this bug with newer version of Ubuntu MATE?