The check that keeps Audio Passthrough out of the in-player settings
sheet dragged the first Scrollable ten times and then asserted the
label was absent. That scrolling never moved: at the pumped 900x700
viewport the sheet fits its own content, so maxScrollExtent is 0 and
the offset stays there through every drag. The assertion passed
identically with no drags at all.
It caught a reintroduced toggle only because the whole list happens to
sit in the element tree at rest. Grow the sheet, shrink the viewport or
give it a lazy delegate and findsNothing starts passing because the
label is offscreen rather than gone, with nothing in the test to say
so.
Land on the audio block that used to hold the toggle first, then
assert the absence. scrollUntilVisible throws when that block is
missing entirely, so the guard fails loudly instead of quietly
weakening.
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