Grid Lightbox images show in wrong order

zogstrip · May 13, 2026, 9:16am

Thanks @Shauny for the report. It was a fun one to debug and fix

github.com/discourse/discourse

FIX: Preserve original image order in grid lightbox (#39968)

main ← fix-grid-lightbox-order

merged 07:31AM - 18 May 26 UTC

ZogStriP

+247 -3

Inside a `[grid]` block, the lightbox arrow navigation followed column-balanced …DOM order instead of the original markdown order. For four images this resulted in 1, 3, 2, 4 because `Columns` distributes items by height into the shortest column. `lightbox.js` collects items via `querySelectorAll(".lightbox")`, which returns nodes in document order — the same scrambled order the layout algorithm produced. `Columns` now tags each item with `data-lightbox-position` carrying its original index before reordering. A new `sortLightboxItems` helper in `lightbox.js` reorders items within each grid by that attribute before they reach PhotoSwipe. The existing RTL reverse continues to apply on top, so right-to-left navigation now mirrors logical order rather than the scrambled layout. https://meta.discourse.org/t/402817

cc @davidb

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Grid Lightbox images show in wrong order

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