First you need to enable the option on Bubble settings to expose an option to add an ID attribute to HTML elements: - Go to your app's settings
- Open the "General" tab
- Find the option "Expose the option to add an ID attribute to HTML elements" and tick it's checkbox

Inside the editor, click on the input element you want to enable a mention dropdown and write the ID you want to use on the property "ID Attribute" at the end of the element's property menu (this ID can be anything)

Add a "@Mention Input" element on your page and set the property "Element ID" to the same ID you've put on the input element. Fill the property "Mention list" with a search of your database that retrieves a list of texts you want to use.
(Example: you have a field on the User thing named 'Username' and you want to enable users to mention each other using this username field, on the "Mention list" property you should put 'Search for User's Username')

And that's it !

If you have any questions, go to jpdom.bubbleapps.io and use the contact form, we respond within 24 hours max.