editor/sagas: focus editor when activated

When a file is activated, it is an indication that the user wants to
edit the file right now, so the editor should be focused.

CHANGELOG.md

@@ -4,6 +4,9 @@
 
 ## [Unreleased]
 
+### Changed
+- Focus editor when new file is opened.
+
 ## [2.2.0-beta.1] - 2023-03-08
 
 ### Added

src/editor/sagas.ts

@@ -238,6 +238,8 @@ function* handleEditorActivateFile(
         editor.restoreViewState(file.viewState);
         activeFileHistory.push(action.uuid);
 
+        editor.focus();
+
         yield* put(editorDidActivateFile(action.uuid));
     } catch (err) {
         yield* put(editorDidFailToActivateFile(action.uuid, ensureError(err)));