feat: return cursor to marked location when exiting toolbox (#210)

* feat: return cursor to marked location when exiting toolbox

* chore: update documentation

Author: rachel-fenichel

src/navigation.ts

@@ -538,10 +538,13 @@ export class Navigation {
   }
 
   /**
-   * Moves the cursor to the top connection point on on the first top block.
-   * If the workspace is empty, moves the cursor to the default location on
-   * the workspace.
-   *
+   * Sets the cursor location when focusing the workspace.
+   * Tries the following, in order, stopping after the first success:
+   *  - Resume editing by putting the cursor at the marker location, if any.
+   *  - Resume editing by returning the cursor to its previous location, if any.
+   *  - Move the cursor to the top connection point on on the first top block.
+   *  - Move the cursor to the default location on the workspace.
+   * 
    * @param workspace The main Blockly workspace.
    * @param keepPosition Whether to retain the cursor's previous position.
    */
@@ -554,6 +557,13 @@ export class Navigation {
     if (!cursor) {
       return;
     }
+
+    if (this.markedNode) {
+      cursor.setCurNode(this.markedNode);
+      this.removeMark(workspace);
+      return;
+    }
+
     if (cursor.getCurNode() && keepPosition) {
       // Retain the cursor's previous position since it's set.
       return;