i didn't try to write a post function but (check with FF (firebug) if i do provide a reference to the rendered AC-list there you can use prototype to add a onClick [take a look at the rendere] and/or write your own renderer
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via the rendere DefaultHTMLRender --> search
} else if (this.type === "xmltohtmllist") {
...
then you can see how the li items (wich passed...
it is not yet implemented
search for ......
afterUpdateElement: function (inputField, selectedItem) {
autocomplete.handler(selectedItem);
}
.....
in AutocompleteTag (ajaxtags.js)
and change the line that is will fit for you.
file a bug request (reopen #1256399).
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try to use onUpdate in the input-field?.