Patch and comparison appearance ownership

Baseline: TortoiseGit 7338078f8ddd924b8cddee35f512f2286072136d.

Source behavior and macOS adaptation

TortoiseUDiff MainWindow.cpp SetTheme/SetSciStyles reapplies editor, caret, selection and diff styles together with the configured UDiff font. UDiffColors.h retains separate light and dark palettes: the normal dark background is #202020, added dark is #104010 and removed dark is #402020. TortoiseMerge BaseView.cpp selects state colors from DiffColors, including the source's high-contrast-dark path. These are independent semantic colors.

The embedded Commit patch inherits its containing window's current appearance. Standalone Unified Diff follows the application appearance until its own Dark Mode command explicitly chooses a window override. General's Follow System, Light and Dark choices therefore reach windows that have no local override. Native selection uses AppKit semantic selection colors. Unified Diff's existing Increase Contrast adaptation uses semantic foreground/background colors; it is not a claim of identical Windows high-contrast policy.

The text view, its scroll view and clip view share the same canvas color, including an empty patch and the area beyond the last line. Palette/font changes restyle the displayed text without replacing its content, clearing Undo or resetting selection, Find or scroll position. Source addition/removal/hunk roles and configured font/tab width remain independent of appearance choice.

Comparison palette ownership

Each comparison or merge model owns an immutable palette loaded from its own preferences. Settings Apply tells open models to read their own store. A private settings window cannot install its palette into another window's renderer. The shared standard-domain facade remains available to consumers without a window owner.

The owned palette reaches normal and combined comparison rows, editable merge results, whitespace and ending marks, inline changes, locator bars, line counts and the line-difference preview. Text, scroll and clip surfaces use Normal's background. Live appearance changes invalidate display without replacing the document. Long documents use the existing TextKit layout path; there is no separate virtualized comparison renderer to claim as an independently tested UI.

Verification boundary

The grouped checkpoint records a repaired Debug build and all three native families passing with both system and bundled Git. Actual embedded and standalone patch views, comparison panes and editable merge results retain content, selection, Undo, Find and scroll across appearance changes. Real Stage/Unstage and Settings Apply are exercised with independent repository witnesses and private preference suites. All six receivers were reaped and independently absent. Core code was unchanged and was not retested.

The first build caught a redundant invalid window reference; its affected rebuild passed. The native fixture initially attempted to write SwiftUI's read-only contrast environment. That unsupported injection was removed without changing production or executable workflow assertions; Increase Contrast remains open. Offscreen public view bitmaps show editor canvases but omit some compositor, material and button content. They are diagnostic captures, not complete dialog screenshots. The earlier signed Finder acceptance exposed the white embedded patch; its installed application predates this repair.

Physical Increase Contrast, VoiceOver, every source state, minimum supported macOS, Intel hardware and signed App Store acceptance remain open. This bounded family does not certify visual parity of every upstream dialog.