Whilst implementing this, we noticed that on some mobile phones there were still some issues:

a) If you have a jquery-ui dialog box open, it could be nigh impossible to use the close icon in the top right hand
corner on some phones.
After some experimentation, we found that we had to check if the screen size <= 480 and in that case, set the dialog 
"draggable" setting to false

Presumably the phone was struggling to work out if we were trying to drag a box which might only be a couple of pixels smaller
than the width of the screen, or we wanted to hit the close icon.