feat: add different background color for inactive panes

book/src/themes.md

@@ -269,6 +269,7 @@ These scopes are used for theming the editor interface:
 | Key                               | Notes                                                                                          |
 | ---                               | ---                                                                                            |
 | `ui.background`                   |                                                                                                |
+| `ui.background.inactive`          | Background of unfocused document                                                               |
 | `ui.background.separator`         | Picker separator below input line                                                              |
 | `ui.cursor`                       |                                                                                                |
 | `ui.cursor.normal`                |                                                                                                |

helix-term/src/ui/editor.rs

@@ -98,6 +98,10 @@ impl EditorView {
         let text_annotations = view.text_annotations(doc, Some(theme));
         let mut decorations = DecorationManager::default();
 
+        if !is_focused {
+            surface.set_style(area, theme.get("ui.background.inactive"))
+        }
+
         if is_focused && config.cursorline {
             decorations.add_decoration(Self::cursorline(doc, view, theme));
         }