The line-lock from the previous fix made anchors immovable across lines —
dragging a handle vertically no longer extended the selection, losing the
native multi-line behaviour.
New contract: a handle anchor moves RELATIVE to its own visual line. The
finger's vertical displacement from the grab position, in whole visual line
heights, selects the target line (under half a line: the anchor's own
line); the finger's x is projected onto that line. A stationary or
horizontal drag never moves the anchor off its line (the grab-box press
stays safe — the original bug is gone), while a deliberate vertical drag
walks the anchor across lines. The mapping is relative, not the finger's
absolute line, because the 48dp grab box is centred below the line: a low
press tracking the finger's absolute line would first drag the anchor the
wrong way, through a collapse, before reaching the anchor's line.
Verified on device: end handle dragged down extends the selection across
the newline; start handle dragged up extends it onto the previous line;
horizontal drags still shrink along the line without clearing. Tests
mutation-verified against both the pre-fix mapping and the
absolute-finger-line variant. Docs section 17 updated.
Greg Pomerantz
7239b1e7ae