#446 chunk C: Complex surfaces (editor, scrollbars, terminal)

[JDonaghy]

Sub-task of #446 — Migrate GTK draw wiring to ScreenLayout::draw()

Scope (chunk 3 of 4): Complex content surfaces

Migrate the editor viewport, scrollbars, and terminal — these already have their own layout patterns (EditorLayout, TerminalSplitLayout) so should be structurally simpler than chunk B.

Surfaces:

• Editor viewport — Surface::Editor, EditorLayout already exists (quadraui#197)
• Editor scrollbars (vertical + horizontal) — Surface::Scrollbar
• Terminal + terminal split — Surface::Terminal, TerminalSplitLayout already exists (quadraui#196)

Branch: continue on issue-446-screen-layout-draw after chunk B merges.

Depends on

• #446 chunk B: Hit-test chrome surfaces (tab bars, status bars, breadcrumbs) #461 (chunk B)

Related

• Parent: Migrate GTK draw wiring to quadraui ScreenLayout::draw() #446
• Previous chunk: #446 chunk B: Hit-test chrome surfaces (tab bars, status bars, breadcrumbs) #461
• Next chunk: #446 chunk C: Complex surfaces (editor, scrollbars, terminal) #462 (popups)

[JDonaghy]

Implementation notes (2026-05-18, coordinator)

Last chunk of #446. These surfaces have their own layout structs already — same pattern as chunk D (popups).

Surfaces:

• Editor viewport — Surface::Editor, EditorLayout exists (quadraui#197)
• Editor scrollbars (vertical + horizontal) — Surface::Scrollbar
• Terminal + terminal split — Surface::Terminal, TerminalSplitLayout exists (quadraui#196)

Also consider:

• Find/replace overlay — Surface::FindReplace
• Toast stack — Surface::Toast
• Palette (all pickers) — Surface::Palette

These may have been partially covered by chunk D. Check what's left in src/gtk/draw.rs that still calls b.draw_*() directly.

Approach: grep for remaining b.draw_ calls in src/gtk/draw.rs — those are the surfaces still to migrate. Each one becomes a Surface::X push onto a QScreenLayout.

Pull quadraui first: cd ~/src/quadraui && git pull

Files: src/gtk/draw.rs, possibly src/gtk/mod.rs.