Searchable text entry box / drop down menu: is that possible?

Note that it isn't necessary to actually set up a server/ajax interaction.  The web object itself can contain all of the suggestions in the javascript file directly.

 This approach is far more self-contained, as it doesn't depend on setting up an AJAX url, or availability of PHP.  I'd probably start with that first, and only move to a real AJAX type interaction if there was something dynamic, such as access to a database.  

I'd approach this problem perhaps differently.  Captivate enables embedding of an html element, called a "web object"  onto any slide.   The web object can be anything, including a javascript-driven or ajax-driven text entry box with suggestions.    The development of this function can be done entirely outside of captivate.   Captivate includes web objects as an IFRAME.  

IFRAMESs have the wonderful capability that, if the web object is hosted on the same server as the course itself,  the IFRAME can communicate directly  - and bidirectionally  - with it's parent using javascript.   The operational strategy would be that,  once a user has completed the text entry,  the parent ( captivate course ) can simply check to see what value was added and use it as needed.   You can even send "events" from the IFRAME up to the parent to indicate that the user has added/changed something.  

The power of web objects is one of the most underappreciated capabilities in captivate.  

sdwarwick@elearningocean.com for more information. 

Captivate's interactivity is event-based.  The Text-Entry Box object only has a few events you can use.  Each and every keystroke entered IS written to the associated User Variable attached to that Text Entry Box, but you don't have the option of executing an Action on each keystroke.

To achieve the kind of functionality you want would require some fancy JavaScript coding, probably requiring event listeners that reacted to each user keystroke and then ran custom functions to work out what to show based on the user's input.