How to add an icon or a button to the right side of the top panel

@Darya thank you for the discussion!

You can use the ApplicationShell#addWidget to add your widget (button, icon, menu, etc.) to the topPanel and style your element to the right with CSS.

Ex:

this.applicationShell.addWidget(widget, { area: 'top' });

Where to write this code

@tt2592 any use of the framework, additional implementations, customizations would need to be contributed in your own custom extension.