Do you want to request a feature or report a bug?

Report a bug.

What's the current behavior?

Recently, div in EventCell was changed to button (#987).
This causes issues because we can't add clickable elements in a button on Firefox (https://stackoverflow.com/questions/50173408/clickable-div-inside-a-button-doesnt-work-on-firefox).

In our case, we have the Event which is a div with a custom onMouseClick attached to it but this callback doesn't get fired because of the surrounding button.

Moreover, this is syntactically incorrect to put interactive content in button, they are reserved for phrasing content (source).

What I suggest, to keep the accessibility and to be compliant, it's to change the button to a div and to add a tabindex={0} to it. It will add it to the list of tappable elements (source) so the behavior will be unchanged.

What's the expected behavior?

We should be able to add a custom logic to click on events.