Dialog

The one dialog frame for both devices: a fixed heading with ×, a scrolling body with a persistent scrollbar, and a footer only when there is a decision.

Consumer provides: title (and optional subtitle), body content, footer actions (or none), width class.

Anatomy

Frame: surface, 2 dp ink (stroke-frame), radius-md. No scrim, shadow or dim layer — the heavier line separates it from the page.
Heading: title + optional muted subtitle, × IconButton on the trailing edge. Divider under it only when the body scrolls.
Body: scrolls; persistent Scrollbar.
Footer: only for decisions; actions trailing, Cancel (outlined) before the primary. Divider above it only when the body scrolls.

Sizes

	Tablet	Phone
Pickers, confirmations	`dialog-narrow` 400 dp, centred	confirmations: centred 343 dp dialog with the 2 dp frame; pickers: BottomSheet
Prompts: short forms, sign-in steps	`dialog-narrow` 400 dp, centred	centred 343 dp dialog with the 2 dp frame
Default	`dialog-standard` 560 dp, centred	BottomSheet
Editors	`dialog-editor` 720 dp, capped at width − 48	BottomSheet
Lists (Meeting notes, Topics), Settings	560 × 800 dp, search and count in the heading	BottomSheet

Tablet padding: heading 24 / 24 / 16, body 16 top · 24 start · 32 end, footer 16 / 24 / 24; title tablet-title.

Rules

×, system Back and tapping outside dismiss. With Cancel + Save, all three act as Cancel.
No footer and no "Close" button on dialogs with nothing to confirm (Settings, libraries, About).
Confirmations have no ×: the choice is the footer. Title names the thing; body names the consequence.
Size to content: pickers never use the default width.

In the app

InkPopover is the frame; InkDialog adds the heading, body and footer.

Size classes (DialogSize): Confirmation, Narrow and Prompt 400 dp, Standard 560 dp, Editor 720 dp, List 560 × 800 dp fixed height.
Tablet: every size is capped at the screen width − 48 dp. (Phone sizes are full-width sheets; see BottomSheet.)
The tablet frame has no window animation.
On the phone, every size except Confirmation and Prompt is a BottomSheet.
Phone confirmations and prompts are centred 343 dp dialogs with the 2 dp frame and no scrim. A prompt keeps its × when it is dismissible.
Every sign-in and sign-up step, including “Checking your subscription…”, is a Prompt, so the flow never switches between a sheet and a centred dialog.
Every dialog window (StaticDialogWindow) keeps the status bar hidden like the activity, so an editor never shifts under a dialog.
Phone heading: at least 64 dp tall, title in Title Large.
The 48 dp × acts exactly like Cancel, as do Back and outside taps.
Phone body padding: 8 dp top · 16 dp start · 24 dp end, including the scrollbar lane.
Confirmations (MessageDialog): Cancel, then the confirm action, filled red when destructive.
Custom popovers with lazy lists use InkDialogHeading for the same heading.

Preview

Tablet · centred, 560 dp (drawn at 1:1 dp, here 480)

Confirmation (both devices)