Bug Report

Steps to reproduce

1. open https://dev.agiletoolkit.org/demos/interactive/tabs.php
2. click "Dynamic Form" tab
3. click (quickly - before the AJAX completes) other/"Hello" tab
4. notice when the AJAX load of "Dynamic Form" tab finishes, the "Hello" tab is replaced

related with atk4/ui#2244

Expected result

When tab is switched, any ongoing async load must be canceled.

Actual result

Tab content must never be replaced with content of different tab.

Version

2.9.3/latest