Add application-title-bar widget-specific options

[HeitorAugustoLN]

Implements third-party widget-specific options for application-title-bar as suggested in #229

[magnouvean]

Other than that it looks OK for the most part I reckon. I don't really have time to test all these options though, but maybe I'll test a few of them tomorrow and see if they generally work. In the future we should maybe also add an option to add the widget automatically to extraWidgets, but the interface isn't really there yet so that can be done in another pr.

[HeitorAugustoLN]

Other than that it looks OK for the most part I reckon. I don't really have time to test all these options though, but maybe I'll test a few of them tomorrow and see if they generally work.

As far as I tested, everything should be working right now.

In the future we should maybe also add an option to add the widget automatically to extraWidgets, but the interface isn't really there yet so that can be done in another pr.

That is a good idea, I could try doing it later.

[magnouvean]

Nice that has done the trick. I'll merge right away then as this looks good. Great work!

[HeitorAugustoLN]

Thanks!