How to add a new object to the panel through dconf configuration

[vojtapolasek]

Hello, @cwendling for awareness.
I am creating a Fedora remix focused on needs of blind and visually impaired called Vojtux.
Here is the project URL: https://github.com/vojtapolasek/vojtux
I am trying to perform only minimal modifications to the Mate panel, so that I accidentally do not cause more harm.
Basically, my use case would be to add to the panel the "Advanced Mate menu" object.
I would like to add it programmatically. I created a simple RPM package called vojtux-settings which ships some dconf overrides. You can see its current state here:
https://github.com/vojtapolasek/vojtux/tree/master/rpm/vojtux-settings

In the past, I inserted into the override quite a lot of things, basically overriding the whole panel configuration. I thought this might not be necessary.
You can see in this PR: vojtapolasek/vojtux#89 that I drastically shrinked the override file.
But now the "Advanced mate menu" object does not get added.
Please is there a way in which I would say: take whatever is on the panel by default and add this one more object? Here it is called object-0.
Thank you,
Vojta

[lukefromdc]

I for one do not know how to do that through dconf

[vojtapolasek]

@lukefromdc and do you know how to do it programmatically in a different way? For example by running a command? Thank you.

[lukefromdc]

I've only ever done it from the Add To Panel dialog. I do NOT know how to configure the panel by program. In fact, when I am testing panel changes if my layout gets screwed up I have to reset everything by hand,

[cwendling]

For a distribution, I'd still recommend creating a custom panel layout (under /usr/share/mate-panel/layouts/) and make it default with a GSettings override. AFAIK it requires re-defining everything, but it allows easy resetting, and makes it independent of other changes.

However, if you want to programmatically add one applet, it's also doable. It's not trivial, but here's the gist of it:

• get the toplevel (panel) ID you want to add the applet to. There's basically 3 ways to do it:

  • know the ID beforehand
  • get one more or less randomly from org.mate.panel toplevel-id-list (maybe the first one?)
  • get the one associated with a known applet, e.g. org.mate.panel.object:/org/mate/panel/objects/notification-area/ toplevel-id

  You might want to try different ones if the preferred solution fails.

• set the various properties of the new applet, e.g. object-type, applet-iid and toplevel-id at least for an applet. The values need to be set on a new object path, e.g. org.mate.panel.object:/org/mate/panel/objects/the-new-applet/ -- the name is the name of the object, it can be anything you like, here I used the-new-applet, but you should use something unique but a bit more specific. You could use extra care not to re-use an existing name, and possibly check ahead if the object you're trying to add isn't there already.

• optionally, you might want to query a known applet to position the new one relative to it (to set position and panel-right-stick).

• update org.mate.panel object-id-list to include your new object name.

I did that in a shell script, but I wouldn't recommend this. Prefer using a real language with a GSettings binding, like e.g. Python.

I don't think there is a way to use e.g. GSettings overrides for this, because you need to modify org.mate.panel object-id-list. I don't remember if you can set specific paths with GSettings overrides as well, but if you can you could do most changes that way, but still need to update the object-id-list anyway.

[vojtapolasek]

Thank you very much @cwendling for the exhaustive description.
I will archive this and use it if I need it.
The reason is that in the end, I decided to abandon adding the applet programmatically and I will just use dconf override.
Why? Because originally, I wanted to distribute an RPM package which would depend on the mate-menu and after installation, it would add the menu to the panel. So that the user does not have to do it manually.
Therefore, it could be used to provision a live environment (by merely including the custom package in the kickstart) but I thought it could be also installed to existing Fedora, making the life of blind users easier.
But that was the point where I found out that it is not achievable, at least I think so.
Because in case we want to insert this configuration into existing Fedora, the dconf override will not work because each user can already have their own panel layout, panel configuration etc.
So this is not doable in RPM scriptlet.
I will solve it with documentation. Let me know if you think there might be another way to achieve this.