Relative urls on user controls

[Microsoft Newsserver]

Hi,

I have a conundrum and want advice on the cleanest way to solve it.

I have some images on a web user control ( not written by me ) which is used
in many places and I need to find a mouseover image swap solution which
works wherever the control is situated and regardless of if it is deployed
or not.

The images are facilitated in image button controls which are actioned when
the user clicks on them. so I add the mouseover attributes on pre-render of
the control and pass 'this' and the desired image string ie
'images/fastForward.gif' which needs to appear from the root of the
application ( not necessarily the root of the server ).

So the question is how best to determine the root of the application and
make this available so that I can use the image swap function in jscript to
swap them out.