A tidier header bar and a collapsible differences panel.
- The differences panel can now be hidden and brought back with a header bar button or Ctrl+D, giving the editors the full window height. Opening the graph view hides it automatically and closing the graph restores it.
- Secondary header bar actions (differences, graph, history, format) are now icon buttons with tooltips and accessible labels, so the header stays compact on narrow windows.
- Fixed symbolic icons that rendered as outlines invisible on dark themes: the bundled fallbacks are now fill-based, which is what GTK recolors.
- Every icon the app uses now ships a bundled fallback, so no packaging channel can show a broken-image placeholder when the desktop icon theme lacks a name.
- The Debian/APT package now ships the bundled SQL language definition, restoring SQL syntax highlighting for .deb installs.