[data grid] When wrapping custom renderHeader components in a Tooltip, it alway shows on hover, still appearing when there is no ellipsis about mui-x HOT 3 OPEN

yes, that is expected behavior.
We do have some excessive logic on this topic to only show a tooltip when there is an ellipsis in place. If you want to mimic this behavior you would need to add similar logic to control it.

from mui-x.

that's too bad, it would be great if we could just enable that logic on the field.

from mui-x.

that's too bad, it would be great if we could just enable that logic on the field.

That would not work.
Think of the custom render header as a standalone component.

What you can do is listening on the events columnHeaderOver, columnHeaderOut, columnHeaderEnter or columnHeaderLeave to trigger your custom Tooltip.

from mui-x.