Checklist

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Summary

For accessibility purposes (especially section 508 testing and compliance), being able to control the tabindex property is helpful for keyboard navigability.

Why?

As a package, Streamlit is currently unintentionally hostile to accessibility patterns and standards due to reliance on iframes with insufficient ability for developers to control rendered page output. Allowing tabbing control helps in ensuring the page can be keyboard navigable, and starts to help screen reader compatibility.

How?

The streamlit.elements.iframe.IframeMixin class supports src, width, height, and scrolling objects that are passed to the protobuf object that is defined in the generated protobuf code at streamlit.proto.IFrame_pb2.py.

If this is the right place to put it, it would be helpful to add an optional argument to control the tab index set between -1, 0, and other values.

Additional Context

No response