The "Beneficial Spells in Effect" window rendered its rows only in the top
249px and painted the rest of the list as empty black background, with a
scrollbar thumb sized for a viewport far smaller than the visible one. It did
not depend on window size, and the last visible row was sliced mid-height --
a clip boundary, not a missing row.
Root cause is the #412 class again. The authored list element (0x10000123) is
a UiTemplateListBox, not a UiItemList, so EffectsUiController creates the item
list itself and attaches it as a child with fill anchors. That baseline is
captured lazily on the child's first ApplyAnchor -- which lands AFTER the host
has already been resized to the restored window height in the same frame. The
capture then measures a bottom margin of (hostH - 249) and ComputeAnchoredRect
preserves it forever: h = hostH - (hostH - 249) = 249, at every subsequent
size. Rows past 249px fail LayoutCells' cull test and never draw.
Capturing the baseline at creation, while the list's extent still exactly
equals the host's, makes the margins (0,0,0,0) so it tracks the host from then
on. Identical fix and reason to UiTemplateListBox's own viewport seed. The
spellbook's component list is built by the same pattern and had the same
latent defect; it is fixed alongside.
Why it shipped: every existing test in EffectsUiControllerTests supplies a
synthetic UiItemList as the list element, so `host is UiItemList` is true and
the controller uses it directly -- the create-and-attach branch that actually
runs against real dat was never exercised. The new test binds the real
fixture, which builds the real UiTemplateListBox. Neutralising the fix makes
it fail with the exact production numbers (expected 547, actual 249).
Measured, not guessed. tools/LayoutDump grew --resize, which reproduces
retail's raw-edge policy (UIElement::UpdateForParentSizeChange @ 0x00462640)
offline, and it ruled out the authored geometry, the import, the layout policy
and the window frame in turn -- all four are faithful. The 4px gap between the
scrollbar and the window's inner edge is likewise authored: the user confirmed
retail shows the same gap, so it is deliberately left alone.
Solution builds clean; 14,465 tests pass on the standard hermetic lane filter,
0 failures.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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