Hello,
is there some way to use a React component as a widget in, for example, the sidebar?
We do not yet have support for React components in generic widgets yet – there a feature request on that https://github.com/bryntum/support/issues/774
As a workaround, you could add a Bryntum Widget to sidebar items: https://bryntum.com/docs/calendar/#Calendar/widget/Sidebar#config-items, then grab its element at the runtime and render the React component into it, perhaps with the help of React portals.
Unfortunately, we do not have a demo of that.