Rio

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adr/0142-aqua-theme-appearance-and-font-floor.mdRaw Markdown · GitHub ↗

ADR-0142: On Aqua, the theme reaches the native controls, and chrome text has a floor

  • Status: Accepted
  • Date: 2026-09-29
  • Deciders: jka
  • Decision: D135

Context

A screenshot run on macOS found two faults that no headless check had caught.

  • On Aqua, Tk draws button, menubutton and checkbutton as native controls, which ignore -background. Dark themes (Solarized Dark, night) showed light buttons.
  • Tk converts font points with tk scaling: 1.33 px/pt on X11, 1.0 on Aqua. The theme's UI size 9 was 12px on Linux and 9px on a Mac, below macOS's own interface text.

ADR-0024 (D24) puts every Tk-specific mapping of a theme in the GUI applier.

Decision

The native appearance follows the theme's lightness. On Aqua, apply_theme sets ::tk::unsupported::MacWindowStyle appearance to darkaqua when ui.bg is dark, else aqua, on every toplevel. A Toplevel <Configure> binding catches new ones once their native window exists. Every call is inside catch.

Chrome and chat text have an 11pt floor on Aqua. ensure_fonts raises every named font except RioEditorFont, and every fixed-width chrome literal goes through chrome_font, which applies the same floor. The editor keeps the theme's size and the user's override.

Alternatives considered

  • appearance auto. Rejected. It follows the system setting, not rio's theme.
  • Replacing buttons with styled labels. Rejected. A second button implementation just for Aqua, without keyboard or default-button behaviour.
  • ttk::style theme use clam. Rejected. It gives rio an un-Mac look on a Mac.
  • tk scaling 96/72 on Aqua. Rejected. It also grows the editor to 16px and every dimension given in points.

Consequences

  • Buttons, menubuttons and checkboxes draw dark in a dark theme and light in a light one.
  • Native menus and system dialogs still follow the system setting.
  • Chrome text on a Mac is 11px instead of 9px. X11 and Windows are unchanged.
  • The theme data does not change.
  • On Aqua, rio leaves the colours of buttons and menubuttons to the native appearance; a tinted bezel with rio's text colour was unreadable in a dark theme.
  • Headless checks cover both, and the sixteen screenshot scenes were checked by eye.