Regression in Lua column layouts: forward classes correctly. (#6865)

* regression: forward classes correctly. Closes #6863
* add test

src/resources/filters/layout/columns-preprocess.lua

@@ -83,7 +83,8 @@ function resolveColumnClassesForCodeCell(el)
               local ref_type = crossref.categories.by_name[custom.type].ref_type
               local custom_classes = float_classes[ref_type]
               local custom_caption_classes = float_caption_classes[ref_type]
-              applyClasses(custom_classes, custom_caption_classes, el, childEl, custom, ref_type)
+              -- applyClasses(colClasses, captionClasses, containerEl, colEl, captionEl, scope)
+              applyClasses(custom_classes, custom_caption_classes, el, custom, custom, ref_type)
             else
               local figure = discoverFigure(figOrTableEl, false)
               if figure ~= nil then

tests/docs/smoke-all/crossrefs/float/latex/latex-margin-figure.qmd

@@ -0,0 +1,29 @@
+---
+title: "matplotlib demo"
+format: latex
+_quarto:
+  tests:
+    latex:
+      ensureFileRegexMatches:
+        - ["marginfigure"]
+        - []
+---
+
+Demo
+
+```{python}
+#| echo: false
+#| column: margin
+
+import matplotlib.pyplot as plt
+
+plot = plt.figure()
+plot.set_figwidth(2)
+plot.set_figheight(3)
+
+x = [1, 2]
+y = [2, 3]
+
+plt.plot(x,y)
+
+```