See this https://forumapp3.bubbleapps.io/version-test/reusablecustomstate?debug_mode=true
Click the “Set Custom State” button. That button lives inside the reusable HeaderCustomState element, but triggers the visibility of the hidden shape on the page when clicked.
Here’s the editor https://bubble.io/page?type=page&name=reusablecustomstate&id=forumapp3&tab=tabs-1