There’s not much to go on (and the demo isn’t illustrating the described problem) but the width of the label is set as 100px. That’s short – try increasing it.
That just seems too obvious though and I’m sure there’s more to it – you might need to supply a bit more of the markup and code to put it into context (i.e. more of the plugin and/or sidebar). Once the demo exhibits the problematic behaviour, we’ll be better positioned to advise how to fix it.