fix: Allow undo/redo handler when outside of editor focus.

closes #6533

app/editor/index.tsx

@@ -4,6 +4,7 @@ import { transparentize } from "polished";
 import { baseKeymap } from "prosemirror-commands";
 import { dropCursor } from "prosemirror-dropcursor";
 import { gapCursor } from "prosemirror-gapcursor";
+import { redo, undo } from "prosemirror-history";
 import { inputRules, InputRule } from "prosemirror-inputrules";
 import { keymap } from "prosemirror-keymap";
 import { MarkdownParser } from "prosemirror-markdown";
@@ -586,6 +587,20 @@ export class Editor extends React.PureComponent<
       this.props
     );
 
+  /**
+   * Undo the last change in the editor.
+   *
+   * @returns True if the undo was successful
+   */
+  public undo = () => undo(this.view.state, this.view.dispatch, this.view);
+
+  /**
+   * Redo the last change in the editor.
+   *
+   * @returns True if the change was successful
+   */
+  public redo = () => redo(this.view.state, this.view.dispatch, this.view);
+
   /**
    * Returns true if the trimmed content of the editor is an empty string.
    *