ApplyScrollEdgeMask, which fades a scroll area's content at its top
and bottom edges, walked every vertex the area emitted on every frame
and tested both edges per vertex, even when the content fit without
scrolling and no vertex could ever be written. It now returns before
the walk when neither edge fades.
The fade maths moved unchanged into scroll_edge_fade.h and is tested
against the old inline expression, so rendering is identical. All six
callers benefit without an edit: the Overview address list, Mining's
recent blocks, Console, History, Explorer and Peers.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>