Custom Application Launcher with Application in Terminal enabled should use user-specified terminal emulator

[Norbert]

Steps to reproduce:
1. Install Ubuntu MATE 20.04 LTS
2. Install non-default terminal - Tilix, by `sudo apt-get install tilix`
3. Install terminal-based application - Midnight Commander, by `sudo apt-get install mc`
3. Set Tilix as default terminal in `mate-default-applications-properties` or programmatically:

      gsettings set org.mate.applications-terminal exec "'tilix'"

4. Set Tilix as alternative for x-terminal-emulator by update-alternatives:

      update-alternatives --set x-terminal-emulator /usr/bin/tilix.wrapper
      sudo update-alternatives --set x-terminal-emulator /usr/bin/tilix.wrapper

5. Reboot
6. Add Custom Application Launcher to the MATE Panel:

      Type: Application in Terminal
      Name: mc
      Command: mc

7. Click the icon of just created Custom Application Launcher

Expected results:

* Midnight Commander is opened in the user-defined terminal - in Tilix

Actual results:

* Midnight Commander is default terminal - in MATE Terminal

Notes:
* This also happens with desktop-files installed by Midnight Commander, it opens in MATE Terminal when called from Brisk menu, Classic menu, Compact Menu, Dock, <Alt>+<F1> menu, Advanced Mate Menu (`mate-menu` package)
* What is interesting, the <Alt>+<F2> respects user preferences and uses Tilix
* Also <Ctrl>+<Alt>+<T> opens Tilix as expected.

---

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: mate-panel 1.24.0-2
ProcVersionSignature: Ubuntu 5.4.0-24.28-generic 5.4.30
Uname: Linux 5.4.0-24-generic x86_64
ApportVersion: 2.20.11-0ubuntu27
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: MATE
Date: Mon Apr 20 10:48:51 2020
InstallationDate: Installed on 2020-04-19 (0 days ago)
InstallationMedia: Ubuntu-MATE 20.04 LTS "Focal Fossa" - Beta amd64 (20200419)
SourcePackage: mate-panel
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

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

[Martin Wimpress  (flexiondotorg)]

glib doesn't support `x-terminal-emulator` so the first found supported terminal emulator (which will be mate-terminal in Ubuntu MATE) will be used, regardless of what preferred applications or alternatives have been configured.

This is why panels/launchers will favour mate-terminal in Ubuntu MATE.

[Launchpad Janitor (janitor)]

This bug was fixed in the package ubuntu-mate-settings - 22.04.13

---------------
ubuntu-mate-settings (22.04.13) jammy; urgency=medium

  * Invoke x-terminal-emulator. (LP: #1873750)

 -- Martin Wimpress <email address hidden> Wed, 06 Apr 2022 17:34:04 +0100

[Launchpad Janitor (janitor)]

This bug was fixed in the package mate-desktop-environment - 1.26.0+1ubuntu5

---------------
mate-desktop-environment (1.26.0+1ubuntu5) jammy; urgency=medium

  * Invoke x-terminal-emulator. (LP: #1873750)

 -- Martin Wimpress <email address hidden> Thu, 07 Apr 2022 11:26:51 +0100

[Norbert (nrbrtx)]

For me Application in Terminal are continuing to run in the default MATE Terminal. I have latest Ubuntu MATE 22.04 LTS:

```
$ gsettings get org.mate.applications-terminal exec
'tilix'

$ ls /etc/alternatives/x-terminal-emulator -al
lrwxrwxrwx 1 root root 22 апр 9 19:01 /etc/alternatives/x-terminal-emulator -> /usr/bin/tilix.wrapper
```

Also please note that mate-desktop-environment is not installed on UM 22.04 LTS by default.