ADR 0117: The seam is the grip¶

Status¶

Accepted

Context¶

The join between the editor and the output panel was a short centred bar — 40×2 pixels with six pixels of padding above and below it. It read as an object placed on the layout rather than as the line where one region ends and the next begins, and it did nothing: the panel's height was whatever the layout decided.

Decision¶

A hairline, edge to edge¶

One pixel, full width. A seam runs the width of what it separates; a short bar in the middle is a handle sitting on top of the join rather than the join itself.

Dim until attended, then full¶

Alpha 22% at rest, easing to 100% when the pointer is over it, on the existing fade tier (motion::kFade). A divider is not something to look at while reading code — the same reasoning that dims the gutter in ADR 0014 — but it has to be findable the moment you go looking for it.

Measured, because "looks dimmer" is not a check: the seam's row reads 85 in luminance unhovered and 245 hovered.

Nobody can reliably hit a one-pixel target. The visible line is a hairline and the grab area around it is seven pixels tall, which is the standard trick and the reason the line can be this thin at all.

Dragging resizes, and so do keys¶

Dragging the seam moves the panel's edge with the pointer. The editor above keeps a floor, so the panel cannot be dragged over the whole window leaving nothing to grab it back by.

Ctrl+Shift+Up and Ctrl+Shift+Down do the same in 60-pixel steps, eased on motion::kChrome. They are window commands, not viewport ones: resizing the panel is most wanted while reading it, and the panel has focus then — a viewport binding would never see the key. That was found by trying it, not by reasoning about it.

Dragging is not eased. Animating a drag makes the edge lag the pointer.

Ctrl+J/Ctrl+K already moved the selection (ADR 0069), and the wheel already glided (installSmoothScroll, ADR 0031) — but that filter only sees wheel events, so moving the selection out of view snapped. The arrows and Ctrl+J/Ctrl+K now ease the viewport to where the list wants it.

Consequences¶

Verified by driving the real editor: the seam brightens by 160 levels of luminance on hover, two presses of Ctrl+Shift+Up grow the panel by exactly 120 pixels, and dragging the seam up 100 pixels moves it 100 pixels.

None of that was possible before: the run-ase driver could send keys but not move the pointer, so hover and drag had no way to be tested. It has pointer() and drag() now.

TranslucentBar is no longer used by the output panel. It is still the file browser's row highlight, so it stays.