I know its possible to integrate jQuery within Firefox addons, but are we able to manipulate (animate, move, adjust transparency, etc) XUL elements themselves?
From
Short answer: Yes
Long Answer:
I experimented with it myself. I could only use it in a limited way. Manipulation of XUL elements is possible. But I am having a hard time observing events, since I am pretty new to jQuery - I don't know how to tweak it to observe events at Firefox/XUL level - I don't even know whether tweaking is required :D
Example:
overlay.xul
overlay.js
function hideMe()
{
$('#btnHide').hide();
}
Above code will hide the button when you click on it - basic XUL manipulation with jQuery!
But as I said, try to observe document load and other such events and it gets complicated very quickly (or I don't know much :D).
Update: I tried some effects. Effects.fadeIn() works - but since the transparency properties are set differently in XUL when compared to HTML, the button stays there and in the end, it abruptly disappears. Now it is becoming clear to what extent we can (can't) use jQuery to manipulate XUL.