Add component to main screen for use in plugin

Hi guys,

new to Volumio. Installed it on my RPi + Touchscreen and am loving it as the base for my media player.

To get the feature I want I need to develop a plugin and have read the guides and done first basic steps.
What I cannot find though is information on how to add a component to the main screen, ideally the top bar.
Basically I need an additional button where the playback controls are.

Is it possible to inject this from a plugin or do I have to make changes to the core UI?

Many thanks