The collapsible bar title of the preview: the function signature with a trailing collapse chevron
(and an optional close). The entire bar toggles collapse — Excel/RowZero-style — so the chevron is
just the affordance, not the only hit target; the close button stops propagation so dismissing never
also toggles. onMouseDown is prevented throughout so a click never blurs the textarea being edited.
The collapsible bar title of the preview: the function signature with a trailing collapse chevron (and an optional close). The entire bar toggles collapse — Excel/RowZero-style — so the chevron is just the affordance, not the only hit target; the close button stops propagation so dismissing never also toggles.
onMouseDownis prevented throughout so a click never blurs the textarea being edited.