T58: the terminal shows a scrollbar over its history, which a user asked for in issue #2 after 0.1.5, since a program that takes the mouse takes the wheel: a thumb along the right edge, in Ely's sizes and colors, stands where the view stands, and a drag moves the view through the history; none shows without history

tasks/acceptance.md

@@ -70,6 +70,7 @@ What no check reached: no real KWin drew the blur; of Wayland desktops, only Hyp
 | Copy, paste, bracketed paste, copy on select, OSC 52 | T09 | T09 review | Pass |
 | OSC 8 and plain links on Cmd-press, Ctrl-press off macOS; inside herdr, herdr opens them whole | T09, T45 | `term::links` tests; on macOS with real herdr 0.9.5 and a stand-in `open` on its PATH, Cmd-press on a URL herdr wraps, on its wrapped tail, on an OSC 8 link and on a URL over three rows opened the whole URL and the OSC 8 target, where before the app opened `.../ELYTermin` and nothing; Cmd-hover underlined the long URL across its rows; outside herdr the app opened the URL itself; an OSC 8 link whose label holds `file:///etc/hosts` and whose target is a web page opened the page through herdr, which keeps the target from the terminal while it takes the mouse; Shift-Cmd-press on a plain `file:///etc/hosts` inside herdr the app opened itself, caught by an `NSWorkspace` stand-in | Pass |
 | Focus reporting, title, scrollback limit, find | T10 | `term::find` tests; round 3 failed at the cap, its fix stands on a red-green test | Pass |
+| A scrollbar over the history: a drag on its thumb scrolls, whatever the program does with the wheel | T58 | `term::scrollbar` test: the thumb's share and place follow the history and the view's offset, and a place past either end of the track holds at it; under Xorg's dummy screen, after `seq 1 500`, the thumb stood at the bottom right, a drag to the top showed the first prompt and lines 1 to 39, and one back down lines 220 to 259; with mouse tracking on, the wheel went to the program as reports and did not scroll, while a drag on the thumb showed lines 245 to 284 | Pass |
 | A bell makes no sound; the row marks it | T10, T12 | T12 review | Pass |
 
 ## 6. Main window and layout