Git Graph: selected commit loses its highlight when focus moves to the changed files #65487

Zed version: 1.23.2 (macOS)

Steps

1. Open the Git Graph.
2. Click a commit. The row gets the element.selected background.
3. Click a file in that commit's changed files.

Expected: The selected commit stays clearly marked, so I know which commit I am reviewing.

Actual: The row switches to element.hover (crates/git_ui/src/git_graph.rs, the selected_bg logic). That looks almost the same as a normal hover, so the selection seems to disappear.

Idea: Use a separate color for "selected but not focused", or keep element.selected while focus is inside the same Git Graph view (commit list + changed files).

Related: #65249