Add a Portal component

[cpakken]

Feature request

Base-UI is internally using portals for components like

Please expose the as its own component

Similar to https://www.radix-ui.com/primitives/docs/utilities/portal

[mj12albert]

@cpakken Could you share some details about your use-case for using a portal directly?

As you said, all the components that could have a portal should already provide it

[cpakken]

I have a <ReaderView /> component that I want to maximize to the viewport by portaling out with fixed position. I can use React's native portal but I'd rather use BaseUI's underlying portal if I'm going to be using its other components. This way I don't need to create a separate portal dom node and just keep things consistent

[mj12albert]

Actually the internal portals are just Floating UI's portal: https://github.com/mui/base-ui/blob/master/packages/react/src/select/portal/SelectPortal.tsx#L19

[colmtuite]

@cpakken Do you need focus management for your use case? We have a lite Portal that we use internally that we could export, but it doesn't include focus management.

[cpakken]

@colmtuite that would be nice, there are some control buttons in the <ReaderView />