Adding a button to the top horizontal bar

I would need to add a button to the default top horizontal toolbar through extension paradigm.
the clicking of that button executing a callback or executing a command.

Could you walk me through the steps for it?

Thanks in advance for your help

[original thread by Frederic Canteloup]

[Frederic Canteloup]

hi, I guess I figured out the best option for me was to use MenuModelRegistry. was it the only or recommended way?

I think you can also add a widget to top area with ApplicaitonShell.addWidget(widget, { area: ‘top’ })

[Frederic Canteloup]

thanks, but this one actually showed at the top left corner