Consider the following jsfiddle : https://jsfiddle.net/zL847sqy/
If you type : "title" then tab, then a value, then tab again (or click outside of the field), the search callback is not fired.
Of course one could use the blur callback (as commented in the fiddle) but this is unreliable as you would only want the callback to be fired after a change, not for each blur, imagine a search being performed live after each call to the search callback.
WDYT ?