How do I call some function after an AHAH callback that adds a new item? I've tried 

'#ahah'   =&gt; array(
        "url": "/?q=content/js_add_more/pmemo/field_tracks_disks_chapter", 
    "event": "mousedown", 
    "keypress": true, 
    "wrapper": "field-tracks-disks-chapter-items", 
    "selector": "#edit-field-tracks-disks-chapter-field-tracks-disks-chapter-add-more", 
    "effect": "fade", 
    "method": "replace", 
    "progress": { "type": "throbber" }, 
    "button": { "field_tracks_disks_chapter_add_more": "Add another item" } , 
        'after' : 'myJsFunction'
),


But it is not working.

I wasn't able to find any solutions to this problem.

Thanks for any help.
You could handle ajaxComplete jquery event, which is called right after completion of ajax/ahah requests.