View ▸ Multiple Pages (1–4): rows of pages filled left to right, scrolling
as one canvas, every page editable. Neither reference product stops at two —
LibreOffice takes a column count, Word fits what the window allows — and both
re-zoom for it, so a whole row is fitted when the count changes. A pane is a
grid cell clipped to one page, a view showing only a contiguous slice; two
rows of cells take turns as the upper one. Cost: columns x 2 live views, each
holding the whole document (measured: +94k nodes and +16ms per keystroke per
view at 177 pages).