fix: Ensure widget divs restore focus correctly.

This avoids reintroducing #9203.

core/widgetdiv.ts

@@ -146,6 +146,18 @@ export function hide() {
 
   const div = containerDiv;
   if (!div) return;
+
+  (common.getMainWorkspace() as WorkspaceSvg).markFocused();
+
+  if (returnEphemeralFocus) {
+    returnEphemeralFocus();
+    returnEphemeralFocus = null;
+  }
+
+  // Content must be cleared after returning ephemeral focus since otherwise it
+  // may force focus changes which could desynchronize the focus manager and
+  // make it think the user directed focus away from the widget div (which will
+  // then notify it to not restore focus back to any previously focused node).
   div.style.display = 'none';
   div.style.left = '';
   div.style.top = '';
@@ -163,12 +175,6 @@ export function hide() {
     dom.removeClass(div, themeClassName);
     themeClassName = '';
   }
-  (common.getMainWorkspace() as WorkspaceSvg).markFocused();
-
-  if (returnEphemeralFocus) {
-    returnEphemeralFocus();
-    returnEphemeralFocus = null;
-  }
 }
 
 /**

tests/mocha/widget_div_test.js

@@ -423,5 +423,26 @@ suite('WidgetDiv', function () {
       assert.strictEqual(Blockly.getFocusManager().getFocusedNode(), block);
       assert.strictEqual(document.activeElement, blockFocusableElem);
     });
+
+    test('for showing nested div with ephemeral focus restores DOM focus', function () {
+      const block = this.setUpBlockWithField();
+      const field = Array.from(block.getFields())[0];
+      Blockly.getFocusManager().focusNode(block);
+      const nestedDiv = document.createElement('div');
+      nestedDiv.tabIndex = -1;
+      Blockly.WidgetDiv.getDiv().appendChild(nestedDiv);
+      Blockly.WidgetDiv.show(field, false, () => {}, null, true);
+      nestedDiv.focus(); // It's valid to focus this during ephemeral focus.
+
+      // Hiding will cause the now focused child div to be removed, leading to
+      // ephemeral focus being lost if the implementation doesn't handle
+      // returning ephemeral focus correctly.
+      Blockly.WidgetDiv.hide();
+
+      // Hiding the div should restore focus back to the block.
+      const blockFocusableElem = block.getFocusableElement();
+      assert.strictEqual(Blockly.getFocusManager().getFocusedNode(), block);
+      assert.strictEqual(document.activeElement, blockFocusableElem);
+    });
   });
 });