I am using x-editable js. My x-editable popover is not shown completely.

Hi the problem is that the tootltip is inside a table and with position:absolute so he was searching for his closest parent with position:relative to be positioned.
The parent that he finds is the div with class .collapse. And this class has the property
overflow:hidden;
You have two solutions with css.
One type this in your css. Enables the view of the overflow in the div.
div.collapse {
overflow:visible;
}
Two type this in your css. Remove this div as the relative parent.
div.collapse {
position:static;
}
Your Fiddle http://jsfiddle.net/kGQ2R/6/
I know this is somewhat of a late reply, but I was just struggling with this issue and solved it in a different way which may help other people.
X-editable is based on Bootstrap's Popover plugin, so adding container: 'body' to your .editable() settings (or any other container that is not within your overflow:hidden element) will also fix this problem.
This will most likely only work with the Bootstrap version of X-editable but I haven't checked that.
Edit:
Just add that container option..
$('#username').editable({
container: 'body',
type: 'text',
pk: 1,
url: '/post',
title: 'Enter username'
});