>Can you point to an example what you want? Is there one here on the UT?
When you do a search, you can click on the magnify glass to open a pick list for the "Created from" field, for example. Then, you can type Smith in the last name, hit enter and the list will be refreshed with available options.
But, IFrame necessity in general goes far more than that. Examples are calendar date selection, color selection, showing a small list (not necessarily a pick list) on top of the main container (if this is what the client asks for), show invoices and so on.