Dialog stretchiness has been an ongoing long standing user wish for all dialogs. Daniel wrote to me hoping that I'd echo his complaint about the Filter dialog. Yes you can stretch it but the frames remain less so. The Filter name frame does add a scroll bar at the bottom when a filter name exceeds the width of the frame, which does not increase in size when the overall host dialog stretches out. Ideally we'd be able to stretch/adjust individual sections of such dialog boxes. If memory serves that is dependent upon which GUI tools are being used to generate the dialog. If that tool set doesn't do it then...we don't get it...without a custom entity.
Daniel was writing about Revit 2019. Even when you scroll over to the right completely a filter with a long name gets truncated and you can't read all of the name.
I note that in Revit 2020 a tooltip will appear that displays the full name while the frame does the same truncating even when it has been scrolled completely to the right.
Naturally, we can avoid it if we can use Filter names that are not very long, an easy fix...there's that word again - easy. Easier said than done...it seems.