Menu_Scroll_DrawsAScrollbarWhenTheMarkupItemCountOverflowsTheVisibleRows was
RED at HEAD: <menu> now defaults to the plain style (RetailButtonArt=false,
the "BIG gold/yellow buttons" owner fix), so a markup menu with no style
attribute draws DrawScrollablePopupPlain's flat DrawFill thumb, never the
retail sprite path (DrawPopupScrollbar) the test asserted on.
Fix: give the existing test style="retail" so it keeps proving the retail
sprite path draws ScrollThumbSprite. Add a plain sibling
(Menu_Scroll_DrawsAPlainFlatThumbFillWhenTheMarkupItemCountOverflowsTheVisibleRows)
that proves the DEFAULT (no style attribute) path draws the flat thumb fill:
an untextured (texture=0) quad sized ScrollbarWidth-2 wide, tinted
PlainBorderColor. Untextured DrawFill calls all batch into one texture=0
render segment, so the assertion scans per-quad (6 verts x 8 floats) inside
each segment rather than treating a whole segment as one quad.
Mutation check: commenting out DrawPopupScrollbarPlain's thumb DrawFill call
turned the new test red ("expected a plain flat thumb fill... among the
drawn segments"); restoring the call turns it green again.
tests/AcDream.Plugins.MossTank.Tests: 660/660 (unchanged).
tests/AcDream.App.Tests --filter Markup|Plugin|UiMenu|Slider: 276 passed / 3
skipped / 279 total (was 274 passed / 1 failed / 3 skipped / 278 total).
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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